Characterization of a complementary deoxyribonucleic acid coding for the gamma chain of human fibrinogen.

A number of cDNAs coding for the gamma chain of human fibrinogen have been isolated from a liver cDNA library by employing a synthetic nucleotide mixture as a probe. One of the positive clones was then employed to screen the entire cDNA library of 18000 recombinants, yielding 320 positive clones for the gamma chain. The largest cDNA was 1638 base pairs in length and contained 10 base pairs of poly(G) at the 5'-end followed by 71 base pairs of noncoding nucleotides. The next 78 base pairs coded for a leader sequence that was 26 amino acids in length and included a methionine start signal and a typical hydrophobic core. The following 1233 base pairs coded for 411 amino acids that are present in the mature protein followed by a stop codon of TAA, 207 base pairs of noncoding nucleotides, a poly(A) track of 15 base pairs, and 22 base pairs of poly(C). Specific regions of the cDNA of the gamma chain were then compared with the cDNAs for the alpha and beta chains of human fibrinogen.