Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Higher eukaryotes express multiple isoforms of AMP deaminase (EC 3.5.4.6). In humans, four AMP deaminase variants, termed M (muscle), L (liver), E1, and E2 (erythrocyte) can be distinguished by a variety of biochemical and immunological criteria. Previous molecular studies have reported two genes, AMPD1 and AMPD2, that produce isoform M and L transcripts, respectively. This study identifies a third human AMP deaminase gene, AMPD3. Nucleotide sequence alignments between AMPD3 cDNAs isolated from several human libraries indicate three different extreme 5'-ends. Alternate forms of the AMPD3 cDNAs contain a common 2301-bp open reading frame (ORF) and 3'-untranslated region of 1245 bp. Two of the three forms, however, exhibit additional 5'-end nucleotide sequences that would extend their respective ORFs by 21 and 27 nucleotides. RNase protection analyses and the partial characterization of human AMPD3 genomic clones demonstrate alternative splicing of three different 5'-terminal exons. Western blot analyses detect anti-E-specific immunoreactivity in affinity-purified extracts derived from the bacterial expression of a truncated AMPD3 cDNA. These results are discussed in relation to AMP deaminase isoform diversity.
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PMID:Cloning of human AMP deaminase isoform E cDNAs. Evidence for a third AMPD gene exhibiting alternatively spliced 5'-exons. 140 Apr 1

AMP deaminase (AMPD) is a highly regulated enzymic activity and multiple isoforms of this enzyme are coded for by a multigene family in mammalian species, including man. Isoform L (liver) is the main activity present in adult human liver and is the protein product of the AMPD2 gene, which is widely expressed in non-muscle tissues and cells. A previous report described almost the full-length cDNA sequence and part of the human AMPD2 gene and also presented Northern blot evidence for multiple transcripts in brain. This study was performed to further characterize the AMPD2 gene and its expression in human tissues. AMPD2 genomic and human cerebellum cDNA clones were isolated, sequenced and used as probes in RNase protection analyses which together demonstrated the following: (1) an intervening sequence near the 5'-end of the published AMPD2 cDNA, which affects the predicted N-terminal amino acid sequence of isoform L; (2) alternative transcripts resulting from exon shuffling at, or near, the 5'-end of the AMPD2 gene that exhibit tissue-specific patterns of relative abundance; (3) predicted usage of three different initiation codons to confer variable N-terminal extensions on isoform L polypeptides; and (4) an extension of a 3' untranslated sequence in some AMPD2 transcripts. In addition, reverse transcriptase PCR and additional RNase protection analyses were used to map the 5'-ends of two mutually-exclusive exon 1 sequences, both of which contain multiple transcription-initiation sites. These results are discussed in relation to predicted isoform L diversity across human tissues and cells.
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PMID:Characterization of human AMP deaminase 2 (AMPD2) gene expression reveals alternative transcripts encoding variable N-terminal extensions of isoform L. 852 48