title: Xenopus fibrinogen: characterization of the mRNAs for the three subunits.
abstract: We purified and characterized the mRNAs coding for each of the three subunits of Xenopus fibrinogen. Purification was accomplished by electrophoretic separation of liver polyadenylated RNA in a fully denaturing gel, followed by recovery of the RNA from the gel via transfer to an ion-exchange membrane. This procedure yielded fractions which were highly enriched for the mRNAs for each of the fibrinogen chains. The fibrinogen mRNAs were identified by two methods: (i) in vitro translation followed by subunit-specific cleavage with the proteases thrombin and batroxobin; and (ii) cross-hybridization with cDNA clones for individual subunits of rat fibrinogen. The results demonstrate that the A alpha and gamma chains of frog fibrinogen are each coded by a single mRNA species. The A alpha mRNA is ca. 3,100 nucleotides in length, which is nearly twice the minimum size required to code for the A alpha precursor polypeptide. The gamma chain mRNA comprises about 1,600 bases and includes only a small untranslated region. In contrast, the B beta subunit is synthesized from two mRNAs, one of which is 2,500 and the other 1,800 nucleotides long. The 2,500-base mRNA includes a large noncoding region, whereas the smaller one is near the minimum required size. The larger B beta mRNA is ca, fivefold more abundant that the smaller species.
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D005340:Fibrinogen / Q000096:biosynthesis / Q000235:genetics*; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism; D011487:Protein Conformation; D011498:Protein Precursors / Q000302:isolation & purification; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D014982:Xenopus laevis / Q000235:genetics*
chemical_list: D011498:Protein Precursors; D012333:RNA, Messenger; D005340:Fibrinogen