The EC domains of human fibrinogen420 contain calcium binding sites but lack polymerization pockets.
Blood
; 92(10): 3669-74, 1998 Nov 15.
Article
em En
| MEDLINE
| ID: mdl-9808560
ABSTRACT
The extended (E) isoform unique to Fibrinogen420 (Fib420) is distinguished from the conventional chain of Fibrinogen340 by the presence of an additional 236-residue carboxyl terminus globular domain (EC). A recombinant form of EC (rEC), having a predicted mass of 27,653 Daltons, was expressed in yeast (Pichia pastoris) and purified by anion exchange column chromatography. Purified rEC appears to be predominantly intact, as judged by N-terminal sequence analysis, mass spectral analysis of the C-terminal cyanogen bromide (CNBr) fragment, and comparison of recognition by epitope-specific monoclonal antibodies. Carbohydrate determination, coupled with analysis of CNBr digestion fragments, confirms N-linked glycosylation at Asn667, the site at which sugar is attached in E. Analysis of CNBr digestion fragments confirms that two disulfide bridges exist at cysteine pairs E613/644 and E780/793. In the presence of 5 mmol/L EDTA, rEC is highly susceptible to plasmic degradation, but Ca2+ (5 mmol/L) renders rEC resistant. No protective effect from plasmic degradation was conferred to rEC by the peptides GPRPamide or GHRP, nor did rEC bind to a GPR peptide column. These results suggest that the EC domain contains a calcium-binding site, but lacks a polymerization pocket. By analogy with the site elucidated in the gammaC domain, we predict that the EC calcium binding site involves residues E772-778 DADQWEE.
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Coleções:
01-internacional
Temas:
Geral
Base de dados:
MEDLINE
Assunto principal:
Fibrinogênio
/
Cálcio
/
Isoformas de Proteínas
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
Blood
Ano de publicação:
1998
Tipo de documento:
Article
País de afiliação:
Estados Unidos