Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Relatively little is known about the transcriptional control of genes expressed late after T cell activation. We have identified four genes expressed 3 to 5 days after T cell activation by alloantigen or mitogen. Here we report the genomic organization of 519, one of these late T cell activation Ag. Analysis of the genomic clone revealed that 519 consists of six exons. Ribonuclease protection experiments indicated that the most abundant transcript arising from this region is an alternatively spliced form of 519, referred to as 520, which lacks exon 2 and is similar in sequence to NKG5, a cDNA identified in NK cells. These experiments also revealed the existence of two other alternatively spliced RNA transcripts, with heterogeneity in exon 2. Primer extension analysis and ribonuclease protection assays demonstrated that there are two prominent start sites for transcription; however, there is no evidence for the NKG5 transcript in T cells, indicating that NKG5 may represent a NK cell-specific form of 520. The 5' flanking region of this gene contains several previously identified sequences involved in transcriptional regulation, as well as some potentially interesting novel conserved motifs.
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PMID:Genomic structure and alternative splicing of 519, a gene expressed late after T cell activation. 131 39

The 52-kD SS-A/Ro protein is one of the antigenic targets strongly associated with the autoimmune response in mothers whose children have manifestations of neonatal lupus. In addition to the cDNA clone we previously reported for the full-length 52-kD SS-A/Ro protein, an interesting MOLT-4 cDNA clone, p52-2, was found to have an internal deletion of 231 nucleotides including the domain encoding the leucine zipper motif. To further investigate the nature of this deletion, genomic DNA clones were isolated from a lambda FIXII library. The complete gene for the full-length 52-kD protein (alpha form, 52 alpha) spans 10 kb of DNA and is composed of seven exons. Exon 1 contains only the 5' untranslated sequence, while the translation initiation codon is located 3 kb downstream in exon 2, which also encodes the three zinc finger motifs. Exon 4 encodes amino acids 168-245, including the coiled coil/leucine zipper domain. Exon 7 is the longest and encodes the rfp-like domain and the 3' untranslated region. The cDNA p52-2 can now be accounted for as a product of alternative messenger RNA (mRNA) derived from the splicing of exon 3 to exon 5, skipping exon 4, which results in a smaller protein (52 beta) with a predicted molecular weight of 45,000. An initial approach to identifying this alternatively spliced form in the human heart used a ribonuclease protection assay. Using an RNA probe corresponding to bases 674-964 of the full-length cDNA, two protected mRNA fragments were identified, a 290-bp fragment corresponding to expression of 52 alpha and a smaller fragment of 144 bp, the predicted size of 52 beta. Using reverse transcription followed by polymerase chain reaction, cDNAs from a 16-wk fetal heart, 24-wk heart, and adult heart were amplified with primers flanking exon 4. Two polymerase chain reaction products were observed in each tissue, one 1.0 kb likely representing 52 alpha and a second 0.78 kb, consistent with 52 beta. The 0.78-kb fragment identified in the 16-wk heart was cloned, and DNA sequencing confirmed the 52 beta type. Immunoprecipitation of in vitro-translated 35S-labeled 52 beta form was performed to evaluate the antigenicity of this novel form of 52-kD SS-A/Ro. 26 (87%) of 30 sera tested from mothers whose children were known to have neonatal lupus immunoprecipitated the 52 beta form.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:52-kD SS-A/Ro: genomic structure and identification of an alternatively spliced transcript encoding a novel leucine zipper-minus autoantigen expressed in fetal and adult heart. 756 1

To examine the mechanisms responsible for tissue-specific, nutritional, and metabolic regulation of the GLUT4/muscle-adipose specific glucose transporter, we isolated and characterized the properties of the rat GLUT4 gene. Examination of the sequenced 2.5-kilobase flanking DNA revealed substantial identity with that of the mouse and human GLUT4 genes, with the greatest degree of sequence identity within the proximal 1000 basepairs up-stream of the GLUT4 open reading frame. Primer extension analysis identified a unique single transcription initiation site 176 basepairs up-stream from the start of translation. However, ribonuclease mapping revealed the presence of a previously undescribed alternatively spliced form of GLUT4 messenger RNA. Approximately 75% of the GLUT4 transcripts consisted of a fully spliced messenger RNA, and 25% was expressed as an unspliced intron-containing species. The ratios of 5' spliced and unspliced messages were invariant in adipose, cardiac, and skeletal muscle tissues. In vitro translation of reporter constructs containing both the spliced and unspliced leader demonstrated a functional difference between these two transcripts, with the unspliced form translated approximately 5-fold more than the fully spliced species. These data demonstrate the presence of 5'-heterogeneity of the GLUT4 transcripts, which underlies differences in translational efficiency in vitro.
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PMID:Characterization of 5'-heterogeneity of the rat GLUT4/muscle-adipose glucose transporter gene product. 772 Jun 44

The temporal changes in the expression of fibronectin and other extracellular matrix genes were studied in rat aortic rings incubated in vitro in a serum-free medium. Changes in all forms of fibronectin mRNA increased progressively during the 24-hour incubation period, although an increase in the alternatively spliced form of fibronectin designated EIIIA was most pronounced. Both collagen and elastin mRNA levels decreased markedly during the 24-hour interval, as did alpha-actin mRNA. The increase in the relative amount of the EIIIA isoform after a 24-hour incubation was also shown using ribonuclease protection assays. In situ hybridization showed the distribution of the induced fibronectin mRNA to be within all cell types, including endothelial cells, medial smooth muscle cells, and adventitial fibroblasts. Localization in the media was not uniform and was clearly identified mainly in clusters of cells distributed throughout the media. The early induction of fibronectin mRNA was inhibited by genistein, implicating tyrosine kinase activation as a causative factor in fibronectin expression. The in vitro changes reported may reflect a phenotypic change in vascular cell types that is both similar to and different from the changes reported in vivo under conditions in which vascular injury and repair occur.
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PMID:Selective induction of an embryonic fibronectin isoform in the rat aorta in vitro. 837 Jan 23