Monoclonal antibodies to the calcium-binding region peptide of human C-reactive protein alter its conformation.
Five mouse mAb were generated against a synthetic peptide corresponding to the proposed Ca(2+)-binding region of human C-reactive protein (CRP). The peptide consists of amino acids 134 to 148 and possesses a calmodulin Ca(2+)-binding sequence. The mAb reacted with a surface epitope(s) on native, intact CRP as well as the closely related pentraxin protein, serum amyloid P-component. Three of the 5 mAb inhibited the Ca(2+)-dependent phosphorylcholine-(PC) binding activity of CRP, but did not bind to the PC-binding region itself. Four of the five mAb also inhibited the recognition of an epitope in the PC-binding site of CRP. Four of the mAb partially, or completely, protected CRP from selective cleavage by pronase between residues 146 and 147. The findings suggest that the Ca(2+)-binding region is on the surface of CRP, has substantial flexibility, and is probably responsible for the allosteric effects of Ca2+ ions on CRP.
Swanson
S J
SJ
Department of Microbiology, Ohio State University, Columbus 43210.
Mullenix
M C
MC
Mortensen
R F
RF
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001665:Binding Sites; D002097:C-Reactive Protein / Q000276:immunology / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D010450:Endopeptidases / Q000494:pharmacology; D000939:Epitopes / Q000032:analysis; D051379:Mice; D008807:Mice, Inbred BALB C; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism*; D010767:Phosphorylcholine / Q000378:metabolism; D011487:Protein Conformation
D000911:Antibodies, Monoclonal; D000939:Epitopes; D010446:Peptide Fragments; D010767:Phosphorylcholine; D002097:C-Reactive Protein; D010450:Endopeptidases; D002118:Calcium