Carboxyl-Terminal Amino Acid Sequences of Two Variant Forms of the γ Chain of Human Plasma Fibrinogen

• Published in: Proceedings of the National Academy of Sciences - PNAS 1988-05, Vol.85 (10), p.3358-3362
• Main Authors: Francis, Charles W., Müller, Elfriede, Henschen, Agnes, Simpson, Patricia J., Marder, Victor J.
• Format: Article
• Language: English
• Subjects: 550200 - Biochemistry; AMINO ACID SEQUENCE; Amino acids; ANIMALS; Base Sequence; BASIC BIOLOGICAL SCIENCES; Biochemistry; BLOOD COAGULATION FACTORS; CHROMATOGRAPHY; COAGULANTS; Complementary DNA; DNA; DNA SEQUENCING; DRUGS; ELECTROPHORESIS; FIBRIN; FIBRINOGEN; Fibrinogen - genetics; Gels; Genetic Variation; GLOBULINS; HEMATOLOGIC AGENTS; HEMOSTATICS; Humans; Introns; LIQUID COLUMN CHROMATOGRAPHY; Macromolecular Substances; MAMMALS; MAN; MESSENGER-RNA; Molecular Sequence Data; MOLECULAR STRUCTURE; NUCLEIC ACIDS; ORGANIC COMPOUNDS; Peptide Fragments - analysis; plasma proteins; PRIMATES; PROTEINS; PURIFICATION; RATS; RECOMBINANT DNA; RNA; RODENTS; SCLEROPROTEINS; SEPARATION PROCESSES; Sequence Homology, Nucleic Acid; Species Specificity; STRUCTURAL CHEMICAL ANALYSIS; Trypsin; Ungulates; VERTEBRATES
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.85.10.3358

The γ chain of human fibrinogen has been shown to be heterogeneous; three forms of various sizes are normally present in plasma. To further characterize the two less prevalent elongated variants, we have purified the three forms of the γ chain, isolated unique tryptic fragments, and sequenced the variant portions of each chain. The intermediate-sized form (γ 55) has a sequence identical to the longest variant (γ 57.5) from residue Val-408 to Pro-423, which is the C terminus of the γ 55 chain. The γ 57.5 chain extends an additional four amino acids. The C-terminal amino acid sequence and corresponding nucleotide sequence of the γ 55 chain show marked similarity with an elongated γ -chain variant of rat fibrinogen. In addition, a remarkable similarity in both amino acid and nucleotide sequence was noted between the human γ 55 chain and the C-terminal extension in human and bovine Aα chains of fibrinogen, which are encoded by the cDNA but are posttranslationally cleaved and are not found in plasma. The findings suggest an evolutionary conservation in this C-terminal amino acid sequence found in both the fibrinogen Aα and γ chains in several species.