title: Identification of B beta chain domains involved in human fibrinogen assembly.
abstract: Fibrinogen chains are assembled in a stepwise manner in the rough endoplasmic reticulum prior to secretion of the final six-chain dimeric molecule. Previous studies indicated that the synthesis of B beta may be a rate-limiting factor in the assembly of human fibrinogen. To determine the domains of B beta which interact with the other two component chains of fibrinogen, deletion mutants of B beta were transiently co-expressed, together with A alpha and gamma chains, in COS cells, and fibrinogen assembly and secretion were measured. Deletion of the COOH-terminal half of the B beta chain (amino acids 208-461) did not affect assembly and secretion. Assembly of A alpha, gamma, and B beta also occurred when the first NH2-terminal 72 amino acids of B beta were deleted, but not when 93 amino acids were deleted. This indicates that the B beta domain between amino acids 73 and 93 is necessary for the assembly of the three fibrinogen chains. This domain marks the start of the alpha-helical "coiled-coil" region of fibrinogen.
authors.affiliation: Lindsley F. Kimball Research Institute, New York Blood Center, New York 10021.
authors.forename: J Z
authors.initials: JZ
authors.lastname: Zhang
authors.forename: C M
authors.initials: CM
authors.lastname: Redman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002461:Cell Line, Transformed; D002522:Chlorocebus aethiops; D004277:DNA, Single-Stranded; D005340:Fibrinogen / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010957:Plasmids; D014162:Transfection
chemical_list: D004277:DNA, Single-Stranded; D005340:Fibrinogen