Showing papers on "Pseudogene published in 1987"
TL;DR: Sequences of somatically rearranged V lambda 1 genes from embryonic and posthatching bursal cells show that diversification of light chain sequences occurs during ontogeny by a segmental gene conversion mechanism which takes place at a frequency of 0.05-0.1 per cell generation between the pseudogene pool and the unique rearranged functional V gene.
679 citations
TL;DR: It is unexpected to find that the intronless autosomal PGK sequence reported here is not a pseudogene, but is rather a functional gene that has retained a complete open reading frame, and is actively expressed in mammalian spermatogenesis.
Abstract: Phosphoglycerate kinase (PGK) (ATP:3-phospho-D-glycerate 1-phosphotransferase, EC 2.7.2.3) is a metabolic enzyme functioning in the Embden-Meyerhof pathway that converts glucose (or fructose) to pyruvate. Two functional loci for the production of PGK have been identified in the mammalian genome. PGK-1 is an X-linked gene expressed constitutively in all somatic cells and premeitotic germ cells. The human PGK-1 gene consists of 11 exons and 10 introns encompassing a region approximately 23 kilobases (kb) in length. PGK-2 is an autosomal gene expressed in a tissue-specific manner exclusively in the late stages of spermatogenesis. In the present study, a molecular analysis of a human genomic clone of PGK-2 originally isolated by Szabo et al. has revealed that this autosomal sequence completely lacks introns and contains characteristics of a processed gene, or 'retroposon', including the remnants of a poly(A)+ tail and bounding direct repeats. Typically such processed sequences form non-functional pseudogenes that have evolved multiple genetic lesions which preclude translation of any transcript into a functional polypeptide. For example, an X-linked processed pseudogene of PGK-1 (psi PGK-1) in humans has been identified and shown to contain premature termination codons in all reading frames. It was therefore unexpected to find that the intronless autosomal PGK sequence reported here is not a pseudogene, but is rather a functional gene that has retained a complete open reading frame, and is actively expressed in mammalian spermatogenesis. Both the unusual conservation of function in this processed PGK-2 gene and its tissue-specific expression in spermatogenesis are best explained as a compensatory response to the inactivation of the X-linked PGK-1 gene in spermatogenic cells before meiosis.
467 citations
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TL;DR: The existence of pseudogenes in vertebrates and their apparent absence from Saccharomyces could be a consequence of the nature of the recombination process that leads to cDNA integration.
307 citations
TL;DR: The observation that individual elements cluster into subfamilies on the basis of the presence or absence of blocks of sequence, or by the linkage of alternative bases at multiple positions, suggests that most L1 sequences were derived from a small number of structural genes.
296 citations
TL;DR: The possibility that STS deficiency results from aberrant X-Y interchange is discussed and monoclonal and polyclonal antibodies to the protein which has been purified and from which partial amino acid sequence data have been obtained.
263 citations
TL;DR: CpG frequency and CpG methylation across part of the human alpha‐globin locus strongly suggests that an ancestral HTF island at the pseudogene became methylated in the germline, and was lost due to the mutability of 5‐methylcytosine.
Abstract: We have analysed CpG frequency and CpG methylation across part of the human alpha-globin locus. Clusters of CpG at the alpha 1 and alpha 2 genes resemble the 'HpaII tiny fragment (HTF) islands' that are characteristic of mammalian 'housekeeping' genes: CpG frequency is not suppressed; testable CpGs are not methylated in DNA from erythroid or nonerythroid tissues, although flanking CpGs are methylated; CpG clusters are approximately 1.5 kb long and extend both upstream and downstream of the alpha-globin transcription start site. These features are not found at genes of the beta-globin locus. The alpha-globin pseudogene (psi alpha 1) is highly homologous to the alpha 2 and alpha 1 genes, but it lacks an HTF island. Sequence comparison shows that a high proportion of CpGs in the alpha 2 gene are substituted by TpG or CpA in the pseudogene. This strongly suggests that an ancestral HTF island at the pseudogene became methylated in the germline, and was lost due to the mutability of 5-methylcytosine.
198 citations
TL;DR: Comparisons of the nucleotide sequences of all four DR beta genes of the DR4 haplotype show that the genes are extensively similar, approximately 90% in both exons and introns, consistent with the notion that the gene arose by duplications that were followed by homogenization through gene conversion.
186 citations
TL;DR: It is shown that the levels of hsc73 mRNA are approximately 5‐fold higher in rapidly growing tissue‐culture cells than in cells whose growth has been arrested by serum starvation, and the gene appears to be subject to more than one form of regulation, mediated by different promoter elements that are intermingled.
Abstract: The isolation and complete DNA sequence of a rat genomic clone encoding hsc73, the major hsp70-like protein found in growing cells is described. Unlike the heat-inducible genes characterized so far, the hsc73 gene is interrupted by introns, and there are also numerous intronless hsc73 pseudogenes in the rat genome. We show that the levels of hsc73 mRNA are approximately 5-fold higher in rapidly growing tissue-culture cells than in cells whose growth has been arrested by serum starvation. The abundance of hsc73 mRNA is not significantly increased by heat shock of either fed or starved cells. The hsc73 promoter contains putative binding sites for transcription factor Sp1, two CCAAT boxes and, surprisingly, two matches to the consensus heat-shock regulatory element. When fused to the CAT gene and transfected into COS or HeLa cells, the promoter is constitutively active, showing only a small induction by heat shock. Deletion of some constitutive elements makes it more strongly heat-inducible. The gene thus appears to be subject to more than one form of regulation, mediated by different promoter elements that are intermingled.
179 citations
TL;DR: A specifically committed progenitor that originates in the embryonic bursa is responsible for long-term maintenance of the B cell population and these properties and the characteristics of the peripheral B cell compartment are discussed in terms of the evolution of the T and B immune systems.
Abstract: A very unusual molecular mechanism is involved in generating the preimmune repertoire in the chicken bursa of Fabricius. A unique rearranged V gene is diversified through a program of segmental gene conversion with a pool of noncoding pseudogenes being used as donors. A specifically committed progenitor that originates in the embryonic bursa is responsible for long-term maintenance of the B cell population. Both these properties and the characteristics of the peripheral B cell compartment are discussed in terms of the evolution of the T and B immune systems.
170 citations
TL;DR: It is found that a maximum of 14 mouse kallikrein genes have the potential to encode functional proteins, and those which are pseudogenes or encode proteins of unknown function are assigned.
167 citations
TL;DR: To understand the molecular basis of congenital adrenal hyperplasia in a patient with the salt‐wasting form of the disease, cloned and characterized his single 21‐hydroxylase B gene and indicated that this microsomal cytochrome P‐450 may be polymorphic.
Abstract: 21-Hydroxylase deficiency which causes congenital adrenal hyperplasia is one of the most common defects of adrenal steroidogenesis. There are two 21-hydroxylase genes in man, A and B, and these have been mapped to the HLA class III region. Only the 21-hydroxylase B gene is thought to be active. To understand the molecular basis of congenital adrenal hyperplasia in a patient with the salt-wasting form of the disease, we cloned and characterized his single 21-hydroxylase B gene. The nucleotide sequence of this gene and a 21-hydroxylase B gene from a normal individual have been determined. Comparison of the two sequences has revealed 11 nucleotide alterations, of which two are in the 5' flanking region, four are in introns, one is in the 3' untranslated region and four are in exons. Two of the differences in exons cause codon changes, with Ser-269 and Asn-494 in the normal 21-hydroxylase B gene being converted to Thr and Ser, respectively. These amino acid substitutions may give an insight into those residues necessary for 21-hydroxylase enzymatic activity. We have also confirmed that the 21-hydroxylase A gene is a pseudogene due to three deleterious mutations in the exons. In addition, comparison of the 21-hydroxylase B gene sequence with other published sequences indicates that this microsomal cytochrome P-450 may be polymorphic.
TL;DR: Hybridisation analysis of restricted human genomic DNA suggests the presence of one other closely related gene within the genome.
Abstract: An ubiquitin cDNA clone was isolated from a human liver cDNA library. This clone contained two complete, and a portion of a third, ubiquitin coding sequences joined head to tail with no spacer peptides. Screening a human genomic library with a probe derived from the coding region of this cDNA identified a large number of cross-hybridising clones. Differential screening of these genomic clones with the 3' non-coding region of the cDNA identified three different 3'-positive clones. Sequence analysis of these three clones revealed: a gene corresponding to the cDNA containing an intron in the 5' non-coding region and coding for three direct repeats of mature ubiquitin, and two related pseudogenes which appear to have arisen by reverse transcription and insertion into the genome. However, one pseudogene contains two repeats of the ubiquitin coding sequence, while the other contains only one. Hybridisation analysis of restricted human genomic DNA suggests the presence of one other closely related gene within the genome.
TL;DR: A model of the origin of repetitive genes was studied by Monte Carlo simulations and it was shown, under realistic values of parameters, that the genetic load for acquiring a new gene is not as large as J.B.S. Haldane suggested.
Abstract: By considering the recent finding that unequal crossing over and other molecular interactions are contributing to the evolution of multigene families, a model of the origin of repetitive genes was studied by Monte Carlo simulations. Starting from a single gene copy, how genetic systems evolve was examined under unequal crossing over, random drift and natural selection. Both beneficial and deteriorating mutations were incorporated, and the latter were assumed to occur ten times more frequently than the former. Positive natural selection favors those chromosomes with more beneficial mutations in redundant copies than others in the population, but accumulation of deteriorating mutations (pseudogenes) have no effect on fitness so long as there remains a functional gene. The results imply the following: (1) Positive natural selection is needed in order to acquire gene families with new functions. Without it, too many pseudogenes accumulate before attaining a functional gene family. (2) There is a large fluctuation in the outcome even if parameters are the same. (3) When unequal crossing over occurs more frequently, the system evolves more rapidly. It was also shown, under realistic values of parameters, that the genetic load for acquiring a new gene is not as large as J. B. S. Haldane suggested, but not so small as in a model in which a system for selection started from already redundant genes.
Journal Article•
TL;DR: The hGH/hCS gene locus was characterized by the localization of at least 27 Alu-type repetitive sequences and identification of three unique sequences in the vicinity of several hGH and hCS genes which define the probable breakpoints of the evolutionary duplication units.
Abstract: Genomic clones containing the closely related genes for human growth hormone (hGH) and chorionic somatomammotropin (hCS) were obtained from genomic bacteriophage lambda and cosmid libraries. The entire GH/CS chromosomal locus was reconstructed utilizing overlapping restriction fragments characterized from the isolated clones. The hGH/hCS locus contains two GH genes and three CS genes spanning 48 kb of DNA in the order: 5'-(hGH-1/hCS-5/hCS-1/hGH-2/hCS-2)-3', confirming analysis of cosmid clones obtained from a different human library (Barsh et al., 1983). To complete the characterization of the hCS genes, the nucleotide sequence of the hCS-5 gene was determined. Sequence analysis revealed a mutation of the 5' splice site at the exon II-intron B boundary, suggesting that the hCS-5 gene is a pseudogene. The nucleotide sequence of an allelic variant of the hCS-2 gene was determined and found to contain a single amino acid substitution and the deletion of a single codon. The hGH/hCS gene locus was further characterized by the localization of at least 27 Alu-type repetitive sequences and identification of three unique sequences in the vicinity of several hGH and hCS genes which define the probable breakpoints of the evolutionary duplication units. These data, combined with the nucleotide sequences of all five GH and CS genes, indicate that the hGH/hCS gene locus has evolved by duplication mechanisms. Evidence for the occurrence of at least one gene conversion event involving the hCS-1 gene precursor and the hCS-2 gene was found, indicating that the hGH/hCS gene locus has evolved by concerted mechanisms. The structure of the hCS genes is discussed in light of recent studies of CS genes from other mammalian species.
01 Feb 1987
TL;DR: In this article, Barsh et al. reconstructed the entire human growth hormone (hGH) and chorionic somatomammotropin (hCS) chromosomal locus using overlapping restriction fragments characterized from isolated clones.
Abstract: Genomic clones containing the closely related genes for human growth hormone (hGH) and chorionic somatomammotropin (hCS) were obtained from genomic bacteriophage lambda and cosmid libraries. The entire GH/CS chromosomal locus was reconstructed utilizing overlapping restriction fragments characterized from the isolated clones. The hGH/hCS locus contains two GH genes and three CS genes spanning 48 kb of DNA in the order: 5'-(hGH-1/hCS-5/hCS-1/hGH-2/hCS-2)-3', confirming analysis of cosmid clones obtained from a different human library (Barsh et al., 1983). To complete the characterization of the hCS genes, the nucleotide sequence of the hCS-5 gene was determined. Sequence analysis revealed a mutation of the 5' splice site at the exon II-intron B boundary, suggesting that the hCS-5 gene is a pseudogene. The nucleotide sequence of an allelic variant of the hCS-2 gene was determined and found to contain a single amino acid substitution and the deletion of a single codon. The hGH/hCS gene locus was further characterized by the localization of at least 27 Alu-type repetitive sequences and identification of three unique sequences in the vicinity of several hGH and hCS genes which define the probable breakpoints of the evolutionary duplication units. These data, combined with the nucleotide sequences of all five GH and CS genes, indicate that the hGH/hCS gene locus has evolved by duplication mechanisms. Evidence for the occurrence of at least one gene conversion event involving the hCS-1 gene precursor and the hCS-2 gene was found, indicating that the hGH/hCS gene locus has evolved by concerted mechanisms. The structure of the hCS genes is discussed in light of recent studies of CS genes from other mammalian species.
TL;DR: Comparison of the human and murine L-myc gene sequences indicate that the relatively large 5' and 3' untranslated regions are evolutionarily conserved, but that these sequences are totally divergent between the L-, c-, and N- myc genes.
Abstract: We have determined the nucleotide sequence and transforming activity of the human L-myc gene and a processed L-myc pseudogene (L-myc psi). We demonstrate by cotransformation assays that a 10.6-kb EcoRI fragment derived from a human placental library contains a complete and functional L-myc gene including transcriptional regulatory sequences sufficient for expression in rat embryo fibroblasts. Organization of the L-myc gene was determined by comparing its sequence to those of the L-myc psi gene and an L-myc cDNA clone derived from a human small cell lung carcinoma. Our results show that L-myc has a three-exon organization similar to that of the c-myc and N-myc genes. The putative L-myc gene product consists of 364 amino acids and contains five of the seven homology regions highly conserved between c-myc and N-myc. These conserved regions are located along the entire length of the putative L-myc protein and are interspersed among nonconserved regions. While the putative L-myc gene product is of a smaller size when compared to the c- and N-myc proteins, the relative positions of certain conserved residues occur in corresponding locations along the peptide backbone of the three proteins. In addition, comparison of the human and murine L-myc gene sequences indicate that the relatively large 5' and 3' untranslated regions are evolutionarily conserved, but that these sequences are totally divergent between the L-, c-, and N-myc genes. Finally, we demonstrate that, like the N- and c-myc genes, the L-myc gene can cooperate with a mutant Ha-ras gene to cause malignant transformation of rat embryo fibroblasts in culture. Our analyses clearly prove that L-myc represents a functional member of the myc oncogene family and further delineate structural features that may be important for the common and divergent functions of the members of this gene family.
TL;DR: The rat placental-type glutathione S-transferase (GST-P) gene is isolated from a lambda phage library using GST-P cDNA clone, pGP5 using the canonical promoter "TATA" box found 27 base pairs upstream from the putative cap site.
TL;DR: It is revealed that CDC4 contains a large open reading frame encoding a protein of 779 amino acids, and that the duplicated sequence bears strong homology with the carboxy-terminal segment of this open readingframe.
TL;DR: In the 5' flanking region, partially conserved sequences common to H gene and L-subunit gene (L gene) of the rat may be involved in transcriptional regulation by iron, whereas those conserved only in the H gene of man and the rat imply that other factors may independently control H- Subunit regulation.
Abstract: Ferritin stores iron within a protein shell consisting of 24 subunits of two types, heavy (H) and light (L). According to Southern blotting, the rat genome contains four copies homologous to the H-subunit cDNA (H cDNA). To determine whether only one of these is expressed, H cDNAs isolated from rat liver and heart mRNAs were compared and found to share identical nucleotide sequences. Next, genomic clones for three of the four rat H-subunit loci were isolated. Two were classical processed pseudogenes, whereas the third contained an expressed gene. RNase intron mapping of this expressed gene generated the same exon protection pattern when total RNA from rat liver or heart was used, indicating that this gene accounts for most or all of the H-subunit mRNAs (H mRNAs) in these tissues. Comparison of the expressed rat H-subunit gene (H gene) structure with published sequences for other species displays considerable conservation. The coding sequence of the rat H gene predicts 95% similarity to the human amino acid sequence, thus being more highly conserved than the L-subunit sequence of these species. Near the cap region of the 5' untranslated region, the rat H mRNA displays a 28-nucleotide sequence that is almost totally conserved in the corresponding region of the human, bullfrog, and chicken H mRNA and is also faithfully represented in the rat and human L-subunit mRNAs (L mRNAs), thus making this sequence a prime candidate for involvement in the known translational regulation of both subunits by iron. In the 5' flanking region, partially conserved sequences common to H gene and L-subunit gene (L gene) of the rat may be involved in transcriptional regulation by iron, whereas those conserved only in the H gene of man and the rat imply that other factors may independently control H-subunit regulation.
TL;DR: The P450XXIA2 gene "deletions" widely reported in CAH patients probably represent gene conversions, unequal crossovers, or polymorphisms rather than simple gene deletions.
Abstract: Congenital adrenal hyperplasia (CAH) is a common genetic disorder due to defective 21-hydroxylation of steroid hormones. The human P450XXIA2 gene encodes cytochrome P450c21 [steroid 21-monooxygenase (steroid 21-hydroxylase), EC 1.14.99.10], which mediates 21-hydroxylation. The P450XXIA2 gene may be distinguished from the duplicated P450XXIA1 pseudogene by cleavage with the restriction endonuclease Taq I, with the XXIA2 gene characterized by a 3.7-kilobase (kb) fragment and the XXIA1 pseudogene characterized by a 3.2-kb fragment. Restriction endonuclease mapping by several laboratories has suggested that deletion of the P450XXIA2 gene occurs in about 25% of patients with CAH, as their genomic DNA lacks detectable 3.7-kb Taq I fragments. We have cloned human P450c21 cDNA and used it to study genomic DNA prepared from 51 persons in 10 families, each of which includes 2 or more persons with CAH. After Taq I digestion, apparent deletions are seen in 7 of the 20 alleles of the probands; using EcoRI, apparent deletions are seen in 9 of the 20 alleles. However, the apparently deleted alleles seen with Taq I do not coincide with those seen with EcoRI. Furthermore, studies with Bgl II, EcoRI, Kpn I, and Xba I yield normal patterns with at least two enzymes in all cases. Since all probands yielded normal patterns with at least two of the five enzymes used, we conclude that the P450XXIA2 gene "deletions" widely reported in CAH patients probably represent gene conversions, unequal crossovers, or polymorphisms rather than simple gene deletions.
TL;DR: The 5' flanking region of the rat L-gene contains sequences homologous to those in the flanking areas of the human L- and H-genes, suggesting a translational regulatory function of ferritin expression.
TL;DR: The analysis of the structure of the two genes confirm, at the gene level, that transferrins originated by a gene duplication phenomenon and the existence of a new member of the transferrin family, a human transferrin non-processed pseudogene is demonstrated.
TL;DR: The genome of Arabidopsis thaliana (Linnaeus) Heynhold was shown to contain an alpha-tubulin gene family consisting of at least four genes and/or pseudogenes and the primary structure of a transcribed alpha- Tubulin gene was determined.
Abstract: The genome of Arabidopsis thaliana (Linnaeus) Heynhold was shown to contain an alpha-tubulin gene family consisting of at least four genes and/or pseudogenes. The primary structure of a transcribed alpha-tubulin gene was determined. A comparison of the predicted amino acid sequence of the A. thaliana alpha-tubulin with the predicted amino acid sequences of alpha-tubulins of Chlamydomonas reinhardtii, Stylonychia lemnae, and Homo spaiens reveals a high degree of homology; 90%, 87%, and 83% identity, respectively. Thus, a plant alpha-tubulin exhibits a high degree of homology to the alpha-tubulins of protists and animals. The coding sequence of the A. thaliana alpha-tubulin gene is interrupted by four introns, which occur at positions different from those of the less numerous introns of C. reinhardtii and rat alpha-tubulin genes. S1 nuclease mapping data showed that transcription is initiated 99 +/- 1 base pairs upstream from the translation initiation codon. Both 5' and 3' noncoding gene-specific probes were used to examine the expression of the alpha-tubulin gene in leaves, roots, and flowers by hybridization to total RNA isolated from these tissues. The results showed that the alpha-tubulin gene was transcribed in all three tissues.
TL;DR: Genomic DNAs from twelve Japanese patients with steroid 21-hydroxylase deficiency revealed that the 21-OHase B gene of the patient has been converted to the pseudogene, 21- OHase A, as far as the critical 0.5-kb sequence was concerned.
Abstract: Genomic DNAs from twelve Japanese patients with steroid 21-hydroxylase [21-OHase; steroid 21-monooxygenase; steroid, hydrogen-donor:oxygen oxidoreductase (21-hydroxylating); EC 1.14.99.10] deficiency were analyzed by Southern blot hybridization. A 3.7-kilobase (kb) Taq I and a 1.7-kb Pvu II restriction endonuclease fragment that correspond to a 21-OHase B gene were absent from the DNA of two unrelated patients with the salt-wasting form of the disease. However, a 10.5-kb Bgl II fragment corresponding to the region encompassing the 21-OHase B gene was still present in these two patients. The genes encoding 21-OHase were cloned from one of these two patients, who was homozygous by descent for HLA-A26;B39;C4A3;C4B1;DR4. Restriction endonuclease mapping as well as partial nucleotide sequencing analysis revealed that the 21-OHase B gene of the patient has been converted to the pseudogene, 21-OHase A, as far as the critical 0.5-kb sequence was concerned. Thus, the defect was due to both chromosomes each carrying two copies of 21-OHase A pseudogene and lacking functional 21-OHase B gene.
TL;DR: The genomic organization of the replication-independent, basally expressed, human H3.3 gene is atypical of traditional histone gene organization and it is proposed that either the previous assignments of termini of the chicken gene are in error, or there are alternative transcription start and polyadenylation sites.
Abstract: The genomic organization of the replication-independent, basally expressed, human H3.3 gene is atypical of traditional histone gene organization. The gene contains 3 introns totalling 7.8 kb and unusual direct repeats flank all three intron-exon splice junctions. The transcription initiation site was mapped by S1 nuclease protection analysis and confirms that cDNA clones previously reported were full length. Sequence similarities between regions at the 5' and 3' termini of this human gene and a chicken H3.3 gene lead us to propose that either the previous assignments of termini of the chicken gene are in error, or there are alternative transcription start and polyadenylation sites. The 85% base matching of human and chicken H3.3 3'UTR sequences for 520 bases is unprecedented among homolog 3'UTR segments, especially considering that these species are separated by over 250 Myr of evolution. We also present the sequence of three related processed human H3.3 pseudogenes and provide evidence demonstrating that most of the 20 to 30 copies of the H3.3 gene within the human genome are in fact processed pseudogenes.
TL;DR: expression of the gamma-crystallin coding sequences from the human metallothionein IIA promoter in nonlens cells facilitated characterization of the polypeptides encoded by individual gamma-genes and should permit comparison of these proteins with distinct gamma- Crystallins in the human lens.
Abstract: While only two gamma-crystallins have been identified in the human eye lens, molecular studies indicate that the human gamma-crystallins are encoded in a multigene family comprising at least seven closely related members. Sequence analysis of five of these genes has suggested that three (gamma 1-2, G3, and G4) are potentially active, while two (G1 psi and G2 psi) correspond to closely related pseudogenes. Here we report on the detailed structure of a sixth gamma-crystallin gene, G5, and our results obtained with transient expression assays to characterize both the promoter activity and translation products of five members of the gene family. We show that 5'-flanking sequences of G1 psi and G2 psi lacked detectable promoter activity, while the corresponding sequences of G3, G4, and G5 were able to direct high levels of expression of the bacterial chloramphenicol acetyltransferase gene in primary lens epithelia, but not in cultures of nonlens origin. Detailed sequence comparisons indicated that active genes contained several conserved sequence tracts 5' of the TATA box which may constitute functional elements of a lens-specific gamma-crystallin promoter. Expression of the gamma-crystallin coding sequences from the human metallothionein IIA promoter in nonlens cells facilitated characterization of the polypeptides encoded by individual gamma-genes and, in future studies, should permit comparison of these proteins with distinct gamma-crystallins in the human lens.
TL;DR: Five different nucleotide sequences have been found in the human genome homologous to the gene of the α‐subunit of Na+,K+‐ATPase, and a comparative analysis of the primary structure of these genes in the region 749–1328 is presented.
TL;DR: Cl cloning and sequencing the calmodulin-related genes from rat genomic libraries demonstrated that the other two genes are processed pseudogenes generated from the CaMI and CaMII genes, respectively, through an mRNA-mediated process of insertions.
Abstract: We have observed three calmodulin mRNA species in rat tissues. In order to know from how many expressed genes they are derived, we have investigated the genomic organization of calmodulin genes in the rat genome. From a rat brain cDNA library, we obtained two kinds of cDNAs (pRCM1 and pRCM3) encoding authentic calmodulin. DNA sequence analysis of these cDNA clones revealed substitutions of nucleotides at 73 positions of 450 nucleotides in the coding region, although the amino acid sequences of these calmodulins are exactly the same. DNA sequences in the 5' and 3' noncoding regions are quite different between these two cDNAs. From these results, we conclude that they are derived from two distinct bona fide calmodulin genes, CaMI (pRCM1) and CaMII (pRCM3). Total genomic Southern hybridization suggested four distinct calmodulin-related genes in the rat genome. By cloning and sequencing the calmodulin-related genes from rat genomic libraries, we demonstrated that the other two genes are processed pseudogenes generated from the CaMI (lambda SC9) and CaMII (lambda SC8) genes, respectively, through an mRNA-mediated process of insertions. Northern blotting showed that the CaMI gene is transcribed in liver, muscle, and brain in similar amounts, whereas the CaMII gene is transcribed mainly in brain. S1 nuclease mapping indicated that the CaMI gene produced two mRNA species (1.7 and 4 kilobases), whereas the CaMII gene expressed a single mRNA species (1.4 kilobases).
TL;DR: A gene encoding one of the pathogenesis‐related proteins, PR1a, and two related pseudogenes were isolated from Nicotiana tabacum and sequenced and found to have similar structures, including a typical promoter sequence in the 5′‐flanking region.
TL;DR: Three genes from the human cystatin gene family of cysteine-proteinase inhibitors have been isolated from a bacteriophage lambda library containing HindIII digests of human genomic DNA and data combined with genomic Southern-blot analyses show that they form a multigene family with at least seven members.