Mohri H, Tanabe J, Katoh K, Okubo T
First Department of Internal Medicine, Yokohama City University School of Medicine, Japan.
Peptides. 1995;16(2):263-8. doi: 10.1016/0196-9781(94)00180-4.
Fibronectin binds to platelet membrane glycoprotein (GP) IIb/IIIa in both an Arg-Gly-Asp (RGD)-dependent and -independent manner. The identification of an RGD-independent binding domain(s) that interacts with GPIIb/IIIa may be the key to understand the mechanism of thrombus formation. A recombinant fibronectin fragment containing the residues from Ile1359 to Ser1436 (lacking the RGD sequence) had been shown to bind to GPIIb/IIIa in a divalent cation- and activation-dependent manner. To identify a minimal peptide ligand that participates in the recognition of GPIIb/IIIa, we synthesized peptides extending this region, which consist of 12 amino acid residues in length and overlapping by six amino acids. We obtained evidence that two 12-residue peptide sequences from this region (residues 1371-1382 and 1377-1388) inhibit fibronectin binding to GPIIb/IIIa by interacting directly with this receptor, with IC50s of 95 +/- 16 and 104 +/- 19 microM, respectively. These peptides inhibited the binding of fibrinogen to GPIIb/IIIa, as well as ADP-induced platelet aggregation. These results indicate that an RGD-independent GPIIb/IIIa binding site in the cell binding domain of fibronectin was localized within the residues His1377-Ile1382.
纤连蛋白以依赖和不依赖精氨酸 - 甘氨酸 - 天冬氨酸（RGD）的方式与血小板膜糖蛋白（GP）IIb/IIIa结合。鉴定与GPIIb/IIIa相互作用的不依赖RGD的结合结构域可能是理解血栓形成机制的关键。已证明含有从Ile1359至Ser1436残基（缺少RGD序列）的重组纤连蛋白片段以依赖二价阳离子和活化的方式与GPIIb/IIIa结合。为了鉴定参与识别GPIIb/IIIa的最小肽配体，我们合成了延伸该区域的肽，其由12个氨基酸残基组成且彼此重叠6个氨基酸。我们获得的证据表明，该区域的两个12残基肽序列（残基1371 - 1382和1377 - 1388）通过直接与该受体相互作用抑制纤连蛋白与GPIIb/IIIa的结合，IC50分别为95±16和104±19μM。这些肽抑制纤维蛋白原与GPIIb/IIIa的结合以及ADP诱导的血小板聚集。这些结果表明，纤连蛋白细胞结合结构域中不依赖RGD的GPIIb/IIIa结合位点位于His1377 - Ile1382残基内。
