Showing papers on "Intron published in 1980"
TL;DR: Several lines of evidence are presented that suggest a direct involvement of snRNPs in the splicing of hnRNA molecules, including the observation that the nucleotide sequence at the 5′ end of U1 RNA exhibits extensive complementarity to those across splice junctions in hn RNA molecules.
Abstract: Discrete, stable small RNA molecules are found in the nuclei of cells1 from a wide variety of eukaryotic organisms2. Many of these small nuclear RNA (snRNA) species, which range in size from about 90 to 220 nucleotides, have been well-characterised biochemically3–6, and some sequenced7,8. However, their function has remained obscure. The most abundant snRNA species exist as a closely related set of RNA–protein complexes called small nuclear ribonucleoproteins (snRNPs)9. snRNPs are the antigens recognised by antibodies from some patients with lupus erythematosus (LE), an autoimmune rheumatic disease10,11. Anti-RNP antibodies from lupus sera selectively precipitate snRNP species containing Ula7 and Ulb9 RNAs from mouse Ehrlich ascites cell nuclei, whereas anti-Sm antibodies bind these snRNPs and four others containing U2 (ref. 8), U4, US and U6 (ref. 9) RNAs. Both antibody systems precipitate the same seven prominent nuclear proteins (molecular weight 12,000–32,000). All molecules of the snRNAs U1, U2, U4, U5 and U6 appear to exist in the form of antigenic snRNPs9. The particles sediment at about 10S and each probably contains a single snRNA molecule. Indirect immunofluorescence studies (refs 12, 13, and unpublished observations) using anti-RNP and anti-Sm sera confirm the nuclear (but non-nucleolar) location of the antigenic snRNPs. Here we present several lines of evidence that suggest a direct involvement of snRNPs in the splicing of hnRNA. Most intriguing is the observation that the nucleotide sequence at the 5′ end of U1 RNA exhibits extensive complementarity to those across splice junctions in hnRNA molecules.
1,058 citations
TL;DR: It is concluded that not all of these sites are neutral and that they do not behave as accurate evolutionary clocks over long periods of time, but nucleotide substitutions leading to amino acid replacements are an excellent clock.
582 citations
TL;DR: It is concluded that a control region within the gene directs RNA polymerase III to initiate transcription approximately 50 nucleotides upstream from the 5' border of this region.
544 citations
TL;DR: U-1 small nuclear RNA is proposed to be the recognition component of the nuclear RNA splicing enzyme and forms base pairs with both ends of an intron so as to align them for cutting and splicing.
Abstract: The most abundant of the stable small nuclear RNAs of eukaryotic cells, U-1 small nuclear RNA, is exactly complementary to the consensus sequences at RNA splice sites. We propose that this RNA is the recognition component of the nuclear RNA splicing enzyme and forms base pairs with both ends of an intron so as to align them for cutting and splicing.
463 citations
TL;DR: The 12 Interferon (IFN)-related sequences detected in a human gene bank fall into not less than eight distinct classes, indicating that there are at least eight IFN-related genes.
Abstract: The 12 Interferon (IFN)-related sequences detected in a human gene bank fall into not less than eight distinct classes, indicating that there are at least eight IFN-related genes. Most, if not all, of these direct the synthesis of an IFN in Escherichia coli. The sequence of one chromosomal gene and its flanking regions was identical to that deduced for the cDNA corresponding to IFN-αl mRNA. No evidence was found for the existence of an intron, in either the coding or the non-coding segments of the gene.
432 citations
TL;DR: 5S ribosomal RNA specifically inhibits transcription of cloned repeating units of 5S DNA in a nuclear extract of Xenopus oocytes, indicating the presence of large amounts of this protein in these cells can account for both the high rate of synthesis and the subsequent storage of5S RNA to ribosome synthesis.
Abstract: 5S ribosomal RNA specifically inhibits transcription of cloned repeating units of 5S DNA in a nuclear extract of Xenopus oocytes. The inhibition can be explained by the interaction of 5S RNA with a transcription factor that binds specifically to a control region located within the 5S RNA gene. This transcription factor is identical to an abundant cytoplasmic protein that is known to be complexed with 5S RNA in immature Xenopus oocytes. Thus the presence of large amounts of this protein in these cells can account for both the high rate of synthesis and the subsequent storage of 5S RNA to ribosome synthesis.
421 citations
TL;DR: The DNA sequence of the wild type and mutated introns as well as their flanking exons in the yeast mitochondrial gene specifying cytochrome b, and a trans-acting protein "mRNA maturase" responsible for splicing and maturation of cy tochrome b mRNA are determined.
418 citations
TL;DR: The oxi3 locus of yeast mitochondrial DNA has been ascertained to code for Subunit 1 of cytochrome oxidase, which is potentially capable of coding for basic proteins with molecular weights ranging from 30,000 to 80,000.
373 citations
TL;DR: The complete 21S rRNA sequence has been determined for the intron, its junctions and the flanking exon regions of the 21s rRNA gene in three genetically characterized strains differing by their omega alleles (omega+, omega-and omega n) and by their chloramphenicol resistant mutations at the rib-1 locus as discussed by the authors.
325 citations
TL;DR: Analysis of the DNA sequence has revealed that in the strain D273-10B, the cytochrome b gene is composed of three exons, which is somewhat less complex than has been reported for other yeast strains i which exon b1 appears to be further fragmented into three smaller exons.
321 citations
TL;DR: Comparison of the yeast 18 S rRNA sequences with partial sequence data, available for rRNAs of the other eucaryotes, provides strong evidence that a substantial portion of the 18 S RNA sequence has been conserved in evolution.
Abstract: The cloned 18 S ribosomal RNA gene from Saccharomyces cerevisiae have been sequenced, using the Maxam-Gilbert procedure. From this data the complete sequence of 1789 nucleotides of the 18 S RNA was deduced. Extensive homology with many eucaryotic as well as E. coli ribosomal small subunit rRNA (S-rRNA) has been observed in the 3'-end region of the rRNA molecule. Comparison of the yeast 18 S rRNA sequences with partial sequence data, available for rRNAs of the other eucaryotes provides strong evidence that a substantial portion of the 18 S RNA sequence has been conserved in evolution.
TL;DR: Three copies of a highly repetitive DNA sequence B1 which is complementary to the most abundant class of mouse fold-back RNA have been cloned in pBR322 plasmid and sequenced by the method of Maxam and Gilbert and two regions within the B1 sequence which are homologous to the intron-exon junctions are found.
Abstract: Three copies of a highly repetitive DNA sequence B1 which is complementary to the most abundant class of mouse fold-back RNA have been cloned in pBR322 plasmid and sequenced by the method of Maxam and Gilbert. All the three have a length of about 130 base pairs and are very similar in their base sequence. The deviation from the average sequence is equal to 4% and the overall mismatch between each two is not higher than 8%. One of the recombinant clones used contained two copies of B1 oriented in the same direction. All of the B1 copies are flanked with sequences which possess nonidentical but very similar structure. They consist of a number of AmCn blocks (where m varies from 2 to 8 and n equals 1-2). These peculiar sequences in all cases are separated from B1 by non-homologous DNA stretches of 2-8 residues. In one case, a long polypurine stretch is located next to such a block. It consists of 74 residues most of which represent a reiteration of the basic sequence AAAAG. We have found two regions within the B1 sequence which are homologous to the intron-exon junctions, especially to those present in the large intron of the mouse beta-globin gene. It may indicate the involvement of the B1 sequence in pre-mRNA splicing.
TL;DR: The nucleotide sequence was determined for the chicken egg white lysozyme mRNA and for the exons of the gene together with their flanking intron regions to establish the relationship of exons to functional units of the enzyme.
Abstract: The nucleotide sequence was determined for the chicken egg white lysozyme mRNA and for the exons of the gene together with their flanking intron regions. The exon pattern is to some degree related to the structural subdivision of the final protein product. However, the relationship of exons to functional units of the enzyme is better established. Exon 2 codes for amino acids 28-82, which include the catalytically active residues and a cluster of amino acids which bind rings C, D, E, and F of the oligosaccharide substrate. Exon 3 codes for amino acids 82-108, which give additional substrate specificity, determine the cleavage frame for the alternating N-acetylglucosamine/N-acetylmuramic acid chain, and increase the catalytic efficiency of the active center. Exons 1 and 4, respectively, code for translational signal sequences on the mRNA, for the signal peptide of prelysozyme, and for the amino- and carboxy-terminal regions of the enzyme. These regions increase the stability of the molecule but are not directly involved in the catalytic function.
TL;DR: The results imply that the ancestral gene for collagen arose by multiple duplications of a single genetic unit containing a 54 bp condig segment.
TL;DR: Messenger RNA synthesis by the DNA tumour viruses proceeds by a complex but versatile series of transcription and RNA processing steps which allow them to use their genetic information to maximum advantage.
Abstract: Messenger RNA synthesis by the DNA tumour viruses proceeds by a complex but versatile series of transcription and RNA processing steps. The major mechanistic features of this pathway are probably very similar to those used by the animal cell host itself. The viruses have, however, evolved intricate arrangements of protein coding sequences and sites for RNA initiation, polyadenylation and splicing which allow them to use their genetic information to maximum advantage.
TL;DR: Evidence is presented that a homogeneous cytoplasmic species known as 7S RNA is the only abundant RNA in uninfected HeLa cells which can form strong hybrids with the dominant family of middle repetitive DNA sequences in the human genome.
TL;DR: A general method for selecting and characterizing genetically suppressor mutations that restore the respiratory capacity of mit- mitochondrial mutants to uncover the functional circuitry both within the mitochondrial genome and between the mitochondrial and the nuclear genome is developed.
Abstract: To uncover the functional circuitry both within the mitochondrial genome and between the mitochondrial and the nuclear genome, we have developed a general method for selecting and characterizing genetically suppressor mutations that restore the respiratory capacity of mit- mitochondrial mutants. Several hundreds of pseudo-wild type revertants due to a second unlinked mutation which suppresses a target mit- mutation were isolated. The suppressor mutations were found located either in the nuclear (abbreviated NAM for 'nuclear accommodation of mitochondria') or in the mitochondrial genome (abbreviated MIM for 'mitochondrial-mitochondrial interaction'). The specificity of action of various suppressors upon some 250 different mit- mutations located in several genes was tested. According to this specificity of action, suppressors were subdivided into two major classes: allele specific or gene specific suppressors. Because the cob-box mitochondrial gene has a mosaic organization, we were able to find a novel third class of extragenic suppressors specific for mit- mutations within the introns of this gene. Four examples of suppressors showing various specificities of action illustrate our approach. (1) a nuclear gene controlling specific alleles of different mitochondrial genes; (2) a nuclear gene controlling selectively one intron of a split mitochondrial gene; (3) a mitochondrial gene controlling specific alleles of different mitochondrial genes; (4) a region in one complex mitochondrial gene which controls selectively one intron of another split mitochondrial gene. Different mechanisms of suppression are discussed stressing the alleviation of splicing deficiencies of intron mutations.
TL;DR: The structure of the gene suggests that the small palindrome thought to be involved in V/J joining also provides the basis for this abnormal DNA recombination and that the absence of a J segment and RNA splice signal allows an abnormal RNA splicing reaction to occur.
Abstract: A mutant immunoglobulin gene has been formed by an abnormal (non V/J) recombination event such that abnormal RNA splicing is required to form a mutant light chain. The structure of the gene suggests that the small palindrome thought to be involved in V/J joining also provides the basis for this abnormal DNA recombination and that the absence of a J segment and RNA splice signal allows an abnormal RNA splicing reaction to occur.
TL;DR: The intervening sequence in a yeast tyrosine transfer RNA (tRNA Tyr) suppressor gene was deleted in order to test its role in the expression of the gene, and both genes exhibited suppressor function.
Abstract: Many eukaryotic genes contain intevening sequences, segments of DNA that interrupt the continuity of the gene. They are removed from RNA transcripts of the gene by a process known as splicing. The intervening sequence in a yeast tyrosine transfer RNA (tRNA Tyr) suppressor gene was deleted in order to test its role in the expression of the gene. The altered gene and its parent were introduced into yeast by transformation. Both genes exhibited suppressor function, showing that the intervening sequence is not absolutely essential for the expression of this gene.
31 Jul 1980
TL;DR: The nucleotide sequence spanning the ribosomal RNA (rRNA) genes of cloned human mitochondrial DNA reveals an extremely compact genome organization wherein the putative tRNA genes are probably ‘butt-jointed’ around the two rRNA genes.
Abstract: The nucleotide sequence spanning the ribosomal RNA (rRNA) genes of cloned human mitochondrial DNA reveals an extremely compact genome organization wherein the putative tRNA genes are probably ‘butt-jointed’ around the two rRNA genes. The sequences of the rRNA genes are significantly homologous in some regions to eukaryotic and prokaryotic sequences, but distinctive ; the tRNA genes also have unusual nucleotide sequences. It seems that human mitochondria did not originate from recognizable relatives of present day organisms.
TL;DR: The positions of the introns within the ovomucoid gene support the theory that introns separate gene segments that code for functional domains of proteins and provide insight on the manner by which eucaryotic genes were constructed during the process of evolution.
TL;DR: A model suggesting how the phenomenon of switch seen in lymphocytes may occur is presented, suggesting that at least two recombination events occurred to create the gamma 2b gene in MOPC 141.
Abstract: From endonuclease EcoRI partial libraries of DNAs from mouse embryo and MOPC 141, a gamma 2b-producing myeloma, clones were isolated by using a DNA fragment carrying the gamma 2b constant (C) region gene as a hybridization probe. One clone from MOPC 141 contained a heavy chain variable (V) gene and the C gamma 2b gene, as demonstrated by R-loop mapping. The V gene and C gene in this clone were separated by a 3.9-kilobase intron. The characterization of this clone as well as the embryonic clones suggest that at least two recombination events occurred to create the gamma 2b gene in MOPC 141. One of the events is analogous to the V-J joining previously demonstrated in the light chain genes, which brings the major part of the V gene next to a short coding sequence (J). The other event we refer to as "C mu-C gamma 2b switch recombination" because a portion of the intron between the V gene and C gene of the rearranged gamma 2b gene is derived from the 5' flanking sequence of the embryonic C mu gene. A model suggesting how the phenomenon of switch seen in lymphocytes may occur is presented.
TL;DR: Comparison of selected regions of the X and ovalbumin genes indicates that the exon sequences coding for protein and the location of the splice junctions have been well-conserved, and establishes that they have evolved from a common ancestor gene by duplication events.
TL;DR: The methods of enzymatic and chemical treatment of end-labeled RNA were applied to the determination of the nucleotide sequence of chicken and man U 1A RNA and to the reexamination of that of rat U1A RNA indicating high degree of conservation of U1B RNA through evolution.
Abstract: The methods of enzymatic and chemical treatment of end-labeled RNA were applied to the determination of the nucleotide sequence of chicken and man U1A RNA and to the reexamination of that of rat U1A RNA. The chemical method allowed the easy demonstration of the cap structure. All three RNA were 165 nucleotide long. Two hitherto non described modified pyrimidines were detected close to the 5' end. Only 9 base substitutions were observed from chicken to man indicating high degree of conservation of U1A RNA through evolution.
TL;DR: The results point out that the normal sequence of nucleotides in an intron and its flanking sites is necessary but insufficient for the correct splice to occur, and may be a powerful tool for a better understanding of the phenomenon.
TL;DR: Evidence that the excision of the intervening sequence from pre-rRNA occurs in vitro in isolated T. thermophila nuclei is presented, and the resistance of the splicing acticity to concentrations of aurintricarboxylic acid that inhibit other endogenous nucleases should be useful in assaying thesplicing enzyme during purification.
TL;DR: Twenty-nine different SUP4-o tRNATyr genes with second-site mutations were transcribed in X. laevis cell-free RNA polymerase III transcription reactions, and the in vitro transcripts were analyzed by polyacrylamide gel electrophoresis.
TL;DR: An examination of the DNA sequences at the intron/exon junctions suggests that a putative ψβ2 precursor mRNA could not be spliced normally and compares the flanking and noncoding sequences of ψ β2 and β1 and discusses the evolutionary relationship between these two genes.
TL;DR: Saccharomyces cerevisiae transformed with the globin DNA-containing hybrid produced β-globin-specific RNA that lacked 20–40 nucleotides from the 5′ end, contained all of the small intron and extended to about the middle of the large intron, and no splicing of the primary β- globin transcript could be detected in the yeast cells.
Abstract: A 5.1 kilobase-pair segment of rabbit chromosomal beta-globin DNA was joined to pJDB219, a plasmid consisting of pMB9, the 2-mu yeast plasmid and the yeast leu-2 gene. Saccharomyces cerevisiae transformed with the globin DNA-containing hybrid produced beta-globin-specific RNA. As compared to mature beta-globin mRNA, these transcripts lacked 20-40 nucleotides from the 5' end, contained all of the small intron and extended to about the middle of the large intron. Thus, no splicing of the primary beta-globin transcript could be detected in the yeast cells.
TL;DR: The results indicate that viral mRNA synthesis occurs in vitro by multiple initiations at different promoter sites on the genome RNA, and that the elongation and completion of the individual mRNAs depend on prior transcription of 3' proximal genes.