Topic
Exon
About: Exon is a research topic. Over the lifetime, 38308 publications have been published within this topic receiving 1745408 citations. The topic is also known as: exons.
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TL;DR: N-terminal sequencing of the mature wx+ protein leads to the identification of a maize amyloplast-specific transit peptide of 72 aminoacid residues that is associated with tissue-specific expression of the locus.
Abstract: The structure of the wild-type waxy (wx+) locus was determined by sequence analysis of both a genomic and an almost full-size cDNA clone. The coding region comprises 3,718 bp and is composed of 14 exons and 13 small introns. The exons and the promoter region are G/C rich (60%–80%). All three waxy transcripts analysed so far reveal different polyadenylation sites and corresponding polyadenylation signals. The smallest of these mRNAs has a size of 2,263 nucleotides. Northern blot analysis suggests that the tissue-specific expression of the locus is due to transcriptional control. The insertion sites of all transposable element induced waxy mutations analysed have been mapped precisely within the locus. N-terminal sequencing of the mature wx+ protein leads to the identification of a maize amyloplast-specific transit peptide of 72 aminoacid residues.
286 citations
TL;DR: Exon insertions and exon duplications, two major mechanisms of exon shuffling, are shown to involve modules that have introns of the same phase class at both their 5′‐ and 3′‐ends.
285 citations
TL;DR: The loss of heterozygosity observed at chromosome 6q25–q26 may contribute to the initiation and/or progression of cancer by inactivating or reducing the expression of the Parkin gene, another example of a large tumor suppressor gene, like FHIT and WWOX, located at a common fragile site.
Abstract: In an effort to identify tumor suppressor gene(s) associated with the frequent loss of heterozygosity observed on chromosome 6q25–q27, we constructed a contig derived from the sequences of bacterial artificial chromosome/P1 bacteriophage artificial chromosome clones defined by the genetic interval D6S1581–D6S1579–D6S305–D6S1599–D6S1008. Sequence analysis of this contig found it to contain eight known genes, including the complete genomic structure of the Parkin gene. Loss of heterozygosity (LOH) analysis of 40 malignant breast and ovarian tumors identified a common minimal region of loss, including the markers D6S305 (50%) and D6S1599 (32%). Both loci exhibited the highest frequencies of LOH in this study and are each located within the Parkin genomic structure. Whereas mutation analysis revealed no missense substitutions, expression of the Parkin gene appeared to be down-regulated or absent in the tumor biopsies and tumor cell lines examined. In addition, the identification of two truncating deletions in 3 of 20 ovarian tumor samples, as well as homozygous deletion of exon 2 in the lung adenocarcinoma cell lines Calu-3 and H-1573, supports the hypothesis that hemizygous or homozygous deletions are responsible for the abnormal expression of Parkin in these samples. These data suggest that the LOH observed at chromosome 6q25–q26 may contribute to the initiation and/or progression of cancer by inactivating or reducing the expression of the Parkin gene. Because Parkin maps to FRA6E, one of the most active common fragile sites in the human genome, it represents another example of a large tumor suppressor gene, like FHIT and WWOX, located at a common fragile site.
285 citations
TL;DR: The genomic organization of the human ABC1 gene is reported and a frameshift mutation in the ABC2 gene of the index case of Tangier disease is identified, which will be useful in the future characterization of the structure and function of theABC1 gene and the analysis of additional ABC1 mutations in patients withTangier disease.
Abstract: Tangier disease is characterized by low serum high density lipoproteins and a biochemical defect in the cellular efflux of lipids to high density lipoproteins. ABC1, a member of the ATP-binding cassette family, recently has been identified as the defective gene in Tangier disease. We report here the organization of the human ABC1 gene and the identification of a mutation in the ABC1 gene from the original Tangier disease kindred. The organization of the human ABC1 gene is similar to that of the mouse ABC1 gene and other related ABC genes. The ABC1 gene contains 49 exons that range in size from 33 to 249 bp and is over 70 kb in length. Sequence analysis of the ABC1 gene revealed that the proband for Tangier disease was homozygous for a deletion of nucleotides 3283 and 3284 (TC) in exon 22. The deletion results in a frameshift mutation and a premature stop codon starting at nucleotide 3375. The product is predicted to encode a nonfunctional protein of 1,084 aa, which is approximately half the size of the full-length ABC1 protein. The loss of a Mnl1 restriction site, which results from the deletion, was used to establish the genotype of the rest of the kindred. In summary, we report on the genomic organization of the human ABC1 gene and identify a frameshift mutation in the ABC1 gene of the index case of Tangier disease. These results will be useful in the future characterization of the structure and function of the ABC1 gene and the analysis of additional ABC1 mutations in patients with Tangier disease.
285 citations
TL;DR: It is suggested that U1 RNP is essential for the splicing of mRNA precursors, and sera directed against the Sm class of small nuclear RNPs, including a mouse monoclonal antibody, specifically inhibited splicing.
285 citations