Primary structure of bovine Hageman factor (blood coagulation factor XII): comparison with human and guinea pig molecules

Abstract

A bovine Hageman factor cDNA was cloned from a liver cDNA library. The nucleotide sequence was analyzed and the amino-acid sequence was deduced. The sequence deduced was consistent with the partial amino-acid sequences of bovine Hageman factor protein. The sequences for three portions including the amino terminal had been previously reported (Fujikawa et al. (1977) Biochemistry 16, 2270–2278). In comparison with the primary structures of human and guinea pig Hageman factors, the putative domain structures were totally conserved. Each domain possessed high sequence homology with the human molecule (66–88%) and the guinea pig one (63–81%) except for the proline-rich region (less than 10%) which connects the amino-terminal five domains with a serine proteinase portion. Significant heterogeneities were observed among the three species around the essential cleavage sites for the conversion to the activated Hageman factors. Bovine Hageman factor has no suitable amino-acid sequence as the substrate for the trypsin-type proteinases at the proline-rich region in difference from the human and guinea pig molecules. Probably this is the reason why the β-form activated Hageman factor (the proteinase moiety) is not liberated in the activation of the bovine molecule with trypsin or plasma kallikrein.