EVOLUTION OF PROTHROMBIN - ISOLATION AND CHARACTERIZATION OF THE CDNAS ENCODING CHICKEN AND HAGFISH PROTHROMBIN

The cDNA sequences of chicken and hagfish prothrombin have been determ ined. The sequences predict that prothrombin from both species is synt hesized as a prepro-protein consisting of a putative Gla domain, two k ringle domains, and a two-chain protease domain. Chicken and hagfish p rothrombin share 51.6% amino acid sequence identity (313/627 residues) . Both chicken and hagfish prothrombin are structurally very similar t o human, bovine, rat, and mouse prothrombin and all six species share 41% amino acid sequence identity. Amino acid sequence alignments of hu man, bovine, rat, mouse, chicken, and hagfish prothrombin suggest that the thrombin B-chain and the propeptide-Gla domain are the regions mo st constrained for the common function(s) of vertebrate prothrombins.