title: Structural and functional studies on C4b-binding protein, a regulatory component of the human complement system.
abstract: The binding and cofactor activities of C4b-binding protein were examined before and after limited proteolysis by pepsin, trypsin and chymotrypsin. The major fragments generated were characterized by amino acid sequencing, thus establishing the precise points of limited proteolysis. These studies allow a tentative assignment of the cofactor activity site to the residues 177-322 of the 549 amino acid long chain of C4b-binding protein but indicated that residues in the region 332-395 are important in the binding activity.
mesh_terms: D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D002918:Chymotrypsin; D003181:Complement C4 / Q000378:metabolism*; D015935:Complement C4b; D003169:Complement Inactivator Proteins; D006023:Glycoproteins; D006801:Humans; D007700:Kinetics; D010434:Pepsin A; D010446:Peptide Fragments / Q000032:analysis; D014357:Trypsin
chemical_list: D002352:Carrier Proteins; D003181:Complement C4; D003169:Complement Inactivator Proteins; D006023:Glycoproteins; D010446:Peptide Fragments; D015935:Complement C4b; D002918:Chymotrypsin; D014357:Trypsin; D010434:Pepsin A