Carboxy-terminal-extended variant of the human fibrinogen alpha subunit: a novel exon conferring marked homology to beta and gamma subunits.
Similarities between the N-terminal regions of the three subunits of the clotting protein fibrinogen--(alpha beta gamma)2--suggest that they evolved from a common progenitor. However, to date no human alpha chain has been found with the strong C-terminal homology shared by the beta and gamma chains. Here we examine the natural product of a novel fibrinogen alpha chain transcript bearing a separate open reading frame that supplies the missing C-terminal homology to the other chains. Additional splicing leads to the use of this extra sequence as a sixth exon elongating the alpha chain by 35%. Since the extended alpha chain (alpha E) is assembled into fibrinogen molecules and its synthesis is enhanced by interleukin-6, it suggests participation in both the acute phase response and normal physiology.
Fu
Y
Y
Lindsley F. Kimball Research Institute, New York Blood Center, New York 10021.
Weissbach
L
L
Plant
P W
PW
Oddoux
C
C
Cao
Y
Y
Liang
T J
TJ
Roy
S N
SN
Redman
C M
CM
Grieninger
G
G
D000595:Amino Acid Sequence; D001483:Base Sequence; D002478:Cells, Cultured; D004247:DNA; D004591:Electrophoresis, Polyacrylamide Gel; D005091:Exons; D005340:Fibrinogen / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D012326:RNA Splicing; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured
D005340:Fibrinogen; D004247:DNA