Characterization of complementary deoxyribonucleic acid and genomic deoxyribonucleic acid for the .beta. chain of human fibrinogen

Abstract

A total of 148 c[complementary]DNA coding for the .beta. chain of human fibrinogen were identified from a human liver cDNA library employing a bovine cDNA as a probe. The largest cDNA insert contained 1932 base pairs cloned into the PstI site of plasmid pBR322. This cDNA inset contained 66 base pairs coding for a portion or all of a signal sequence, 1383 base pairs coding for 461 amino acids in the mature protein, a stop codon of TAG, a noncodiong region of 431 base pairs, and a poly(A) tail of 19 base pairs. Most of the cDNA inserts coding for the .beta. chain were found to have a noncoding region of 98 or 167 base pairs rather than 431 base pairs at the 3'' end. The bovine cDNA for the .beta. chain was also employed as a probe for screening a .lambda. phage library containing human genomic DNA. Seven positive phage were identified. One of the phage, which contained the entire gene for the .beta. chain of fibrinogen, was examined by EM, and portions of its DNA sequence are presented. Seven intervening sequences were identified in the gene for the .beta. chain of human fibrinogen. The largest intervening sequence (approximately 1.3 kilobases) was found at the 5''-end of the gene and was located between amino acid residues 8 and 9, which are present in fibrinopeptide B. A sequence analysis of the 5''-end of the gene also indicated that the B chain of human fibrinogen contained a signal sequence of either 16, 27, or 30 amino acid residues.