Novel subunit in C4b-binding protein required for protein S binding
(1988) In The Journal of biological chemistry 263(25). p.64-12759- Abstract
C4b-binding protein (C4BP) is a multimeric protein with regulatory functions in the complement system. It also interacts with vitamin K-dependent protein S, which is involved in the regulation of the coagulation system. It has been demonstrated that C4BP consists of seven disulfide-linked, identical 70-kDa subunits, which are arranged to give the molecule a spider-like structure. We now have evidence for the presence of a new subunit in C4BP. On sodium dodecyl sulfate-poly-acrylamide gel electrophoresis it appears as a weakly stainable band with a molecular weight of approximately 45,000. The subunit was isolated by gel filtration in 6 M guanidine hydrochloride of reduced and carboxymethylated C4BP. Its amino-terminal sequence is... (More)
C4b-binding protein (C4BP) is a multimeric protein with regulatory functions in the complement system. It also interacts with vitamin K-dependent protein S, which is involved in the regulation of the coagulation system. It has been demonstrated that C4BP consists of seven disulfide-linked, identical 70-kDa subunits, which are arranged to give the molecule a spider-like structure. We now have evidence for the presence of a new subunit in C4BP. On sodium dodecyl sulfate-poly-acrylamide gel electrophoresis it appears as a weakly stainable band with a molecular weight of approximately 45,000. The subunit was isolated by gel filtration in 6 M guanidine hydrochloride of reduced and carboxymethylated C4BP. Its amino-terminal sequence is distinct from previously known protein sequences. The stoichiometry of 45- to 70-kDa subunits was estimated to be 1:9, indicating the presence of one 45-kDa subunit per C4BP molecule. The new subunit was demonstrated to be a disulfide-linked component of the central core of C4BP. It was sensitive to proteolysis by chymotrypsin, and when cleaved the protein S binding ability of C4BP was lost. With protein S bound to C4BP, the 45-kDa subunit was protected from degradation by chymotrypsin, and the protein S binding site remained intact. These data suggest that the new subunit is directly involved in protein S binding.
(Less)
- author
- Hillarp, A LU and Dahlbäck, B LU
- organization
- publishing date
- 1988-09-05
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Amino Acid Sequence, Binding Sites, Carrier Proteins/isolation & purification, Chromatography, Gel, Chymotrypsin/metabolism, Complement C4, Complement Inactivator Proteins, Disulfides/metabolism, Electrophoresis, Polyacrylamide Gel, Glycoproteins/metabolism, Guanidine, Guanidines, Humans, Immunoassay, Macromolecular Substances, Molecular Sequence Data, Molecular Weight, Peptide Fragments/isolation & purification, Protein S, Receptors, Complement
- in
- The Journal of biological chemistry
- volume
- 263
- issue
- 25
- pages
- 64 - 12759
- publisher
- American Society for Biochemistry and Molecular Biology
- external identifiers
-
- scopus:0024245613
- pmid:2970465
- ISSN
- 0021-9258
- DOI
- 10.1016/S0021-9258(18)37818-9
- language
- English
- LU publication?
- yes
- id
- 25ab1f67-d060-4f00-ac29-b9dbef273a49
- date added to LUP
- 2022-08-29 10:37:02
- date last changed
- 2024-02-18 07:26:26
@article{25ab1f67-d060-4f00-ac29-b9dbef273a49, abstract = {{<p>C4b-binding protein (C4BP) is a multimeric protein with regulatory functions in the complement system. It also interacts with vitamin K-dependent protein S, which is involved in the regulation of the coagulation system. It has been demonstrated that C4BP consists of seven disulfide-linked, identical 70-kDa subunits, which are arranged to give the molecule a spider-like structure. We now have evidence for the presence of a new subunit in C4BP. On sodium dodecyl sulfate-poly-acrylamide gel electrophoresis it appears as a weakly stainable band with a molecular weight of approximately 45,000. The subunit was isolated by gel filtration in 6 M guanidine hydrochloride of reduced and carboxymethylated C4BP. Its amino-terminal sequence is distinct from previously known protein sequences. The stoichiometry of 45- to 70-kDa subunits was estimated to be 1:9, indicating the presence of one 45-kDa subunit per C4BP molecule. The new subunit was demonstrated to be a disulfide-linked component of the central core of C4BP. It was sensitive to proteolysis by chymotrypsin, and when cleaved the protein S binding ability of C4BP was lost. With protein S bound to C4BP, the 45-kDa subunit was protected from degradation by chymotrypsin, and the protein S binding site remained intact. These data suggest that the new subunit is directly involved in protein S binding.</p>}}, author = {{Hillarp, A and Dahlbäck, B}}, issn = {{0021-9258}}, keywords = {{Amino Acid Sequence; Binding Sites; Carrier Proteins/isolation & purification; Chromatography, Gel; Chymotrypsin/metabolism; Complement C4; Complement Inactivator Proteins; Disulfides/metabolism; Electrophoresis, Polyacrylamide Gel; Glycoproteins/metabolism; Guanidine; Guanidines; Humans; Immunoassay; Macromolecular Substances; Molecular Sequence Data; Molecular Weight; Peptide Fragments/isolation & purification; Protein S; Receptors, Complement}}, language = {{eng}}, month = {{09}}, number = {{25}}, pages = {{64--12759}}, publisher = {{American Society for Biochemistry and Molecular Biology}}, series = {{The Journal of biological chemistry}}, title = {{Novel subunit in C4b-binding protein required for protein S binding}}, url = {{http://dx.doi.org/10.1016/S0021-9258(18)37818-9}}, doi = {{10.1016/S0021-9258(18)37818-9}}, volume = {{263}}, year = {{1988}}, }