Human cytoplasmic serine hydroxymethyltransferase is an mRNA binding protein.

摘要: The 5' untranslated region (UTR) of the human cytoplasmic serine hydroxymethyltransferase (cSHMT) message is alternatively spliced, creating a full-length UTR (LUTR) encoded within exons 1-3 and shorter (SUTR) that results from excision exon 2. role UTRs in cSHMT expression was investigated by fusing to end luciferase gene. Human protein at 10 microM inhibits vitro translation UTR-luciferase fusion mRNA templates more than 90%, but does not inhibit lacking UTR. Translation inhibition independent amino acid folate substrate binding enzyme. SUTR-luciferase binds cSHMT.glycine.5-formyltetrahydrofolate ternary complex with an apparent K(d) microM. Gel mobility shift assays demonstrate LUTR-luciferase presence absence glycine 5-formyltetrahydrofolate pentaglutamate. 65 cSHMT-catalyzed cleavage allothreonine as partial mixed type inhibitor, reducing both k(cat) K(m) 40 75%, respectively, while tRNA has no effect on catalysis. These studies indicate can bind mRNA, displays increased affinity for its mRNA.