Li W X, Howard R J, Leung L L
Division of Hematology, Stanford University School of Medicine, California 94305.
J Biol Chem. 1993 Aug 5;268(22):16179-84.
Thrombospondin (TSP) binds to its cellular receptor, CD36 (glycoprotein IV or IIIb), and participates in many adhesive cell interactions. We have shown that the CD36-TSP interaction occurs in a stepwise, conformation-dependent process. CD36 sequence 139-155 binds TSP and induces a second CD36-binding site, which binds CD36 sequence 93-110 with high affinity. To characterize this high affinity CD36-binding site on TSP, an anti-TSP monoclonal antibody (mAb), 7A-1e, was identified that showed augmentation of TSP binding in the presence of CD36 peptide P139-155. Purified mAb 7A-1e IgG specifically blocked both P139-155-augmented CD36 binding and P139-155-dependent CD36 peptide P93-110 binding to TSP, indicating that the binding sites on TSP for mAb 7A-1e and P93-110 are closely related. mAb 7A-1e IgG inhibited collagen-induced platelet aggregation in platelet-rich plasma. SVTCG is a cell adhesive motif in TSP. Both mAb 7A-1e and P93-110 specifically bound to a TSP peptide containing SVTCG, and the binding of mAb 7A-1e or P93-110 to TSP was inhibited by soluble SCTCG peptide. The SVTCG cell adhesive domain in TSP is the conformation-dependent, high affinity binding site for CD36 sequence 93-110.
血小板反应蛋白（TSP）与其细胞受体CD36（糖蛋白IV或IIIb）结合，并参与许多细胞黏附相互作用。我们已经表明，CD36与TSP的相互作用以逐步的、构象依赖性过程发生。CD36序列139 - 155与TSP结合并诱导出第二个CD36结合位点，该位点以高亲和力结合CD36序列93 - 110。为了表征TSP上这个高亲和力的CD36结合位点，鉴定出一种抗TSP单克隆抗体（mAb）7A - 1e，其在存在CD36肽P139 - 155时显示出TSP结合的增强。纯化的mAb 7A - 1e IgG特异性阻断了P139 - 155增强的CD36结合以及P139 - 155依赖性的CD36肽P93 - 110与TSP的结合，表明mAb 7A - 1e和P93 - 110在TSP上的结合位点密切相关。mAb 7A - 1e IgG抑制富含血小板血浆中胶原诱导的血小板聚集。SVTCG是TSP中的一个细胞黏附基序。mAb 7A - 1e和P93 - 110都特异性结合到一个包含SVTCG的TSP肽上，并且可溶性SCTCG肽抑制mAb 7A - 1e或P93 - 110与TSP的结合。TSP中的SVTCG细胞黏附结构域是CD36序列93 - 110的构象依赖性高亲和力结合位点。
