Characterization of a cDNA Clone Coding for the β Chain of Bovine Fibrinogen

Recombinant plasmids containing bovine cDNA have been screened with a radiolabeled cDNA enriched for bovine fibrinogen. A number of plasmids containing cDNAs for fibrinogen were identified by this assay. One plasmid, designated pBI beta 1, was found to contain a cDNA insert of 1372 base pairs. The sequence of the cDNA insert for this plasmid was then determined. It was shown to code for 424 amino acids of the beta chain of fibrinogen, starting with residue 44. This and other data made it possible to construct the complete amino acid sequence of the beta chain of the protein. Comparison of the amino acid sequence of the beta chain of bovine fibrinogen with the corresponding chain of the human molecule indicated that the two chains are greater than 80% homologous.