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)

Complementary DNAs encoding two nonallelic PTH/PTH-related peptide (PTHrP) receptor (PPR) isoforms, xPPR-A and xPPR-B, were isolated from a kidney complementary DNA library of the tetraploid African clawed frog Xenopus laevis. Both isoforms differ in their coding region by 19 amino acids, and lack the region corresponding to the mammalian exon E2. When expressed in mammalian COS-7 cells, both receptor isoforms bound radiolabeled PTH-(1-34) and PTHrP-(1-36) analogs with comparable affinity, and both unlabeled peptides equivalently stimulated the accumulation of cAMP. xPPR-A also mediated inositol phosphate turnover in COS cells and stimulated channel-mediated current changes in voltage clamp experiments after injection into oocytes. Using ribonuclease protection analysis, significant xPPR-A messenger RNA expression was first detected in neurula stage embryos, which subsequently increased approximately 30-fold during tadpole development. Expression reached a maximum at the metamorphotic climax, when isoform B also became detectable at significant levels, and subsequently declined in postmetamorphotic froglets. In the adult frog, xPPR-A was prominently expressed in lung, brain, small bowel, and skin, whereas isoform B was highest in lung, heart, and brain. Using an xPPR-A antisense riboprobe for in situ hybridization, expression appeared during metamorphosis at all sites of chondrogenesis, specifically in the maturing zone of the amphibian growth plate. xPPR-A expression was also seen in a subpopulation of mononuclear cells, possibly representing osteoblasts that line perichondral bone and diaphyseal bone trabeculae. Our findings suggest that xPPRs serve a prominent role in amphibian skeletal development and possibly other functions during embryonal and early larval development.
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PMID:Identification, functional characterization, and developmental expression of two nonallelic parathyroid hormone (PTH)/PTH-related peptide receptor isoforms in Xenopus laevis (Daudin). 944 46

Using sensitive sequence profile searches and contextual information gleaned from domain architectures and predicted operons we identify a novel family of protein domains with predicted ribonuclease activity. These domains are found in the eukaryotic proteins typified by the Nedd4-binding protein 1 and the bacterial YacP-like proteins (Nedd4-BP1, YacP nucleases; NYN domains). We show that the NYN domain shares a common protein fold with two other previously characterized groups of nucleases, namely the PIN (PilT N-terminal) and FLAP/5' --> 3' exonuclease superfamilies. We also show that all these proteins share a common set of 4 acidic conserved residues that are predicted to constitute their active site. Based on the conservation of the acidic residues and structural elements we suggest that PIN and NYN domains are likely to bind only a single metal ion, unlike the FLAP/5' --> 3' exonuclease superfamily, which binds two metal ions. We also present evidence that the other conserved residues shared by all these three domains are likely to play critical roles in sensing the substrate and positioning the catalytic residues in the right conformation. Based on conserved gene neighborhoods we infer that the bacterial members are likely to be components of the processome/degradsome that process tRNAs or ribosomal RNAs. Eukaryotic versions appear to have undergone extensive functional diversification as suggested by the several distinctive multi-domain architectures showing fusions with various other RNA-binding domains like CCCH, PPR and KH domains. Interestingly, the eukaryotic NYN domains also show multiple fusions to the UBA domain, an ubiquitin-binding adaptor domain. This observation, together with the monoubiquitination of Nedd4-BP1 by the ubiquitin ligase Nedd4 suggests that the NYN domain proteins of eukaryotes are regulated by monoubiquitination. Given the localization of Nedd4-BP1 to punctuate nuclear bodies, it is likely that they are parts of nuclear RNA-processing complexes that are dependent on monoubiquitination for their assembly.
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PMID:The NYN domains: novel predicted RNAses with a PIN domain-like fold. 1711 34