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Molecular analysis of the beta-chain of human C4b-binding protein

Hillarp, A LU (1991) In Scandinavian journal of clinical and laboratory investigation. Supplementum 204. p.57-69
Abstract

C4b-binding protein (C4BP) is a multimeric glycoprotein in plasma with important regulatory functions in the complement system. It occurs in two forms, as free protein and in a non-covalent bimolecular complex with the vitamin K-dependent protein S. Protein S is an important anticoagulant and enhances the rate of inactivation by activated protein C of blood coagulation factors, Va and VIIIa. Protein S bound to C4BP is inactive as an anticoagulant, indicating C4BP to have a regulatory function in the blood coagulation process. Approximately 50% of C4BP in plasma circulates in complex with protein S, but little has been known about as to how these proteins interact. This report describes the structure of C4BP and its relation to protein S... (More)

C4b-binding protein (C4BP) is a multimeric glycoprotein in plasma with important regulatory functions in the complement system. It occurs in two forms, as free protein and in a non-covalent bimolecular complex with the vitamin K-dependent protein S. Protein S is an important anticoagulant and enhances the rate of inactivation by activated protein C of blood coagulation factors, Va and VIIIa. Protein S bound to C4BP is inactive as an anticoagulant, indicating C4BP to have a regulatory function in the blood coagulation process. Approximately 50% of C4BP in plasma circulates in complex with protein S, but little has been known about as to how these proteins interact. This report describes the structure of C4BP and its relation to protein S binding. A novel C4BP subunit, designated the beta-chain, which in all likelihood contains the protein S binding site, has been identified, isolated and characterized. The major form of C4BP is composed of seven alpha-chains and one beta-chain, and the subunits are covalently linked by their carboxy-terminal regions giving the molecule a spider-like quaternary structure. A subpopulation of C4BP, which does not bind protein S, was found to lack the beta-chain. This provides support for the concept that the single protein S binding site is located on the beta-chain. The beta-chain is structurally related to the alpha-chain of C4BP, and both subunits belong to the superfamily of C3b/C4b-binding proteins. The genes coding for the alpha- and beta-chains of C4BP were found to be closely linked within a cluster of genes, coding for structurally related proteins, on the long arm of human chromosome 1.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Amino Acid Sequence, Base Sequence, Carrier Proteins/blood, Chromosome Mapping, Chromosomes, Human, Pair 1, Complement Inactivator Proteins, Glycoproteins, Humans, Macromolecular Substances, Molecular Sequence Data, Protein Binding
in
Scandinavian journal of clinical and laboratory investigation. Supplementum
volume
204
pages
57 - 69
publisher
Taylor & Francis
external identifiers
  • scopus:0026035728
  • pmid:2042026
ISSN
0085-591X
DOI
10.3109/00365519109104595
language
English
LU publication?
yes
id
fe83a1ce-82d4-4cfd-af8e-317ac127f601
date added to LUP
2022-08-29 10:33:27
date last changed
2024-01-03 15:55:54
@article{fe83a1ce-82d4-4cfd-af8e-317ac127f601,
  abstract     = {{<p>C4b-binding protein (C4BP) is a multimeric glycoprotein in plasma with important regulatory functions in the complement system. It occurs in two forms, as free protein and in a non-covalent bimolecular complex with the vitamin K-dependent protein S. Protein S is an important anticoagulant and enhances the rate of inactivation by activated protein C of blood coagulation factors, Va and VIIIa. Protein S bound to C4BP is inactive as an anticoagulant, indicating C4BP to have a regulatory function in the blood coagulation process. Approximately 50% of C4BP in plasma circulates in complex with protein S, but little has been known about as to how these proteins interact. This report describes the structure of C4BP and its relation to protein S binding. A novel C4BP subunit, designated the beta-chain, which in all likelihood contains the protein S binding site, has been identified, isolated and characterized. The major form of C4BP is composed of seven alpha-chains and one beta-chain, and the subunits are covalently linked by their carboxy-terminal regions giving the molecule a spider-like quaternary structure. A subpopulation of C4BP, which does not bind protein S, was found to lack the beta-chain. This provides support for the concept that the single protein S binding site is located on the beta-chain. The beta-chain is structurally related to the alpha-chain of C4BP, and both subunits belong to the superfamily of C3b/C4b-binding proteins. The genes coding for the alpha- and beta-chains of C4BP were found to be closely linked within a cluster of genes, coding for structurally related proteins, on the long arm of human chromosome 1.</p>}},
  author       = {{Hillarp, A}},
  issn         = {{0085-591X}},
  keywords     = {{Amino Acid Sequence; Base Sequence; Carrier Proteins/blood; Chromosome Mapping; Chromosomes, Human, Pair 1; Complement Inactivator Proteins; Glycoproteins; Humans; Macromolecular Substances; Molecular Sequence Data; Protein Binding}},
  language     = {{eng}},
  pages        = {{57--69}},
  publisher    = {{Taylor & Francis}},
  series       = {{Scandinavian journal of clinical and laboratory investigation. Supplementum}},
  title        = {{Molecular analysis of the beta-chain of human C4b-binding protein}},
  url          = {{http://dx.doi.org/10.3109/00365519109104595}},
  doi          = {{10.3109/00365519109104595}},
  volume       = {{204}},
  year         = {{1991}},
}