Assembly of protein S and C4b-binding protein on membranes.

Protein S enhances C4b binding protein interaction with neutrophils.

Protein S, an inhibitor of coagulation, interacts reversibly with C4b binding protein (C4bBP). The physiologic role of this complex formation remains unknown. In this study we examined the possibility that protein S would facilitate C4bBP binding to the surface of neutrophils where, in turn, this complex could help protect the cell from complement-mediated damage at the site of inflammation. Ne...

Influence of endotoxin challenge on protein S and C4b-binding protein in healthy subjects.

Binding of C4b-Binding Protein to Porin

We screened 29 strains of Neisseria gonorrhoeae and found 16/21 strains that resisted killing by normal human serum and 0/8 serum sensitive strains that bound the complement regulator, C4b-binding protein (C4bp). Microbial surface-bound C4bp demonstrated cofactor activity. We constructed gonococcal strains with hybrid porin (Por) molecules derived from each of the major serogroups (Por1A and Po...

Complement Inhibitor C4b-Binding Protein

Novel subunit in C4b-binding protein required for protein S binding.

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 ev...