Platelet glycoprotein Ib: a zinc-dependent binding protein for the heavy chain of high-molecular-weight kininogen.
Domains 3 and 5 of high-molecular-weight kininogen (HK) have been shown to bind to platelets in a zinc-dependent reaction. However, the platelet-binding proteins responsible for this interaction have not been identified. We have focused on the platelet-binding site for the heavy chain (domain 3), which we approached using a domain 3-derived peptide ligand and isolated binding proteins by affinity chromatography. The domain 3-derived peptide, thrombin, HK, factor XII, as well as antibody to glycocalicin (the N-terminal portion of the alpha chain of GPIb) recognized a protein at 74 kD. We also isolated the thrombin receptor (PAR 1) at 45 kD, however, none of the above-mentioned ligands bound to this protein. Isolation of platelet membrane proteins using a monoclonal anti-glycocalicin antibody column revealed the same HK binding protein at 74 kD, which was reactive with anti-GPIb and represents a GPIb fragment. By photoaffinity labeling, HK interacted with membrane GPIb, which was then isolated in native form (135 kD) along with gC1qR, a ligand for the HK light chain. Finally, (125)I-HK binding to platelets was significantly inhibited by the anti-GPIb antibody. These results suggest that the GPIb alpha chain, a known thrombin binding protein, is also one of the zinc-dependent platelet membrane binding sites for HK domain 3.
Joseph
K
K
Department of Medicine, Division of Pulmonary, Critical Care, Asthma and Allergy, Medical University of South Carolina, Charleston, South Carolina 29425-2220, USA.
Nakazawa
Y
Y
Bahou
W F
WF
Ghebrehiwet
B
B
Kaplan
A P
AP
D000906:Antibodies; D019921:Biotinylation; D001792:Blood Platelets / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D005174:Factor XII / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D019679:Kininogen, High-Molecular-Weight / Q000097:blood*; D008970:Molecular Weight; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D013917:Thrombin / Q000378:metabolism; D015032:Zinc / Q000378:metabolism* / Q000494:pharmacology
D000906:Antibodies; D019679:Kininogen, High-Molecular-Weight; D019038:Platelet Glycoprotein GPIb-IX Complex; C023592:glycocalicin; D005174:Factor XII; D013917:Thrombin; D015032:Zinc