title: Binding site on human C-reactive protein (CRP) recognized by the leukocyte CRP-receptor.
abstract: C-reactive protein (CRP), the prototypical inflammatory acute phase reactant in humans, interacts with monocytes and neutrophils via a specific receptor. To map the site on CRP recognized by the CRP receptor (CRP-R), synthetic peptides corresponding to the surface region on each of the five identical subunits were tested as competitors vs. [125I]-CRP for cell binding. A peptide of residues 27-38 (TKPLKAFTVCLH) efficiently inhibited CRP binding when compared to other nonoverlapping peptides. This peptide was termed the cell-binding peptide (CB-Pep). The F(ab')2 of an IgG Ab to the CB-Pep specifically inhibited CRP binding upon reacting with the ligand. Competitive binding studies with synthetic peptides truncated from either the NH2- or COOH-terminus of the CB-Pep revealed that the minimum length recognized by the CRP-R consisted of residues 31-36: KAFTVC. Conservative substitutions of residues within the CB-Pep indicated that the four residues AFTV were critical for CRP-R binding. The CB-Pep also inhibited induced superoxide generation by HL-60 granulocytes. The minimum length required for the inhibition was also KAFTVC; however, only Phe-33 and Leu-37 were critical residues in this assay. Anti-CB-Pep IgG Ab reacted more extensively with heat-modified CRP, suggesting that an altered conformation of CRP is preferentially recognized by the CRP-R. The results suggest that this contiguous sequence on a beta-strand on one face of each of five subunits of the CRP pentamer serves as a unique recognition motif for inflammatory leukocytes.
authors.affiliation: Department of Microbiology, Ohio State University, Columbus 43210, USA.
authors.forename: Q
authors.initials: Q
authors.lastname: Zen
authors.forename: W
authors.initials: W
authors.lastname: Zhong
authors.forename: R F
authors.initials: RF
authors.lastname: Mortensen
mesh_terms: D000595:Amino Acid Sequence; D000906:Antibodies / Q000494:pharmacology; D001667:Binding, Competitive; D002097:C-Reactive Protein / Q000276:immunology* / Q000378:metabolism* / Q000494:pharmacology; D018604:Epitope Mapping; D018922:HL-60 Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007948:Leukemia, Monocytic, Acute / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D007962:Leukocytes / Q000378:metabolism*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology / Q000494:pharmacology*; D011971:Receptors, Immunologic / Q000276:immunology / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D000906:Antibodies; C071581:CRP protein, human; D010446:Peptide Fragments; D011971:Receptors, Immunologic; D013481:Superoxides; D002097:C-Reactive Protein