A cluster of basic amino acid residues in the gamma370-381 sequence of fibrinogen comprises a binding site for platelet integrin alpha(IIb)beta3 (glycoprotein IIb/IIIa).
A cluster of basic amino acid residues in the gamma370-381 sequence of fibrinogen comprises a binding site for platelet integrin alpha(IIb)beta3 (glycoprotein IIb/IIIa).
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DOI：
10.1021/bi051581d
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发表时间：
2005-12
期刊：
影响因子：
2.9
通讯作者：
Nataly P. Podolnikova;O. Gorkun;R. Loreth;V. Yee;S. Lord;T. Ugarova
中科院分区：
文献类型：
--
作者：
Nataly P. Podolnikova;O. Gorkun;R. Loreth;V. Yee;S. Lord;T. Ugarova
血小板整合素α（IIb）β 3与纤维蛋白原和纤维蛋白的粘附相互作用是止血和血栓形成的中心事件。然而，α（IIb）β 3结合这些配体的机制仍然不完全清楚。我们最近证明，α（IIb）β 3结合纤维蛋白（原）γ C结构域中的γ 365 -383序列。该序列既不包含AGDV也不包含已知结合α（IIb）β 3的RGD识别基序，表明整合素的不同特异性。在这里，使用肽阵列，突变的纤维蛋白原，和重组突变的γ C-域，我们已经研究了机制，使α（IIb）β 3结合γ 365 -383。α（IIb）β 3结合活性位于γ 370 -381内，其中两个短序列γ 370 ATWKTR 375和γ 376 WYSMKK 381能够独立地结合整联蛋白。此外，gamma 370 -381对alpha（IIb）beta3的识别取决于四个碱性残基：Lys 373、Arg 375、Lys 380和Lys 381。同时替换这些氨基酸和删除重组γ C-结构域中的γ 408 AGDV 411序列导致α（IIb）β 3介导的血小板粘附的丧失。证实了所鉴定的残基的关键作用，异常纤维蛋白原Kaiserplastern，其中γ Lys 380被Asn取代，表现出延迟的凝块收缩和受损的α（IIb）β 3结合。此外，模仿天然存在的变异体Osaka V（γ Arg 375--> Gly）的突变重组纤维蛋白原显示出延迟的凝块收缩和与纯化的α（IIb）β 3的结合减少。这些结果鉴定了纤维蛋白（原）的γ 370 -381序列作为参与血小板粘附和凝块收缩的α（IIb）β 3的结合位点，并定义了这种整合素的新识别特异性。
Adhesive interactions of platelet integrin alpha(IIb)beta3 with fibrinogen and fibrin are central events in hemostasis and thrombosis. However, the mechanisms by which alpha(IIb)beta3 binds these ligands remain incompletely understood. We have recently demonstrated that alpha(IIb)beta3 binds the gamma365-383 sequence in the gammaC-domain of fibrin(ogen). This sequence contains neither the AGDV nor the RGD recognition motifs, known to bind alpha(IIb)beta3, suggesting the different specificity of the integrin. Here, using peptide arrays, mutant fibrinogens, and recombinant mutant gammaC-domains, we have examined the mechanism whereby alpha(IIb)beta3 binds gamma365-383. The alpha(IIb)beta3-binding activity was localized within gamma370-381, with two short sequences, gamma370ATWKTR375 and gamma376WYSMKK381, being able to independently bind the integrin. Furthermore, recognition of alpha(IIb)beta3 by gamma370-381 depended on four basic residues, Lys373, Arg375, Lys380, and Lys381. Simultaneous replacement of these amino acids and deletion of the gamma408AGDV411 sequence in the recombinant gammaC-domain resulted in the loss of alpha(IIb)beta3-mediated platelet adhesion. Confirming the critical roles of the identified residues, abnormal fibrinogen Kaiserslautern, in which gammaLys380 is replaced by Asn, demonstrated delayed clot retraction and impaired alpha(IIb)beta3 binding. Also, a mutant recombinant fibrinogen modeled after the naturally occurring variant Osaka V (gammaArg375 --> Gly) showed delayed clot retraction and reduced binding to purified alpha(IIb)beta3. These results identify the gamma370-381 sequence of fibrin(ogen) as the binding site for alpha(IIb)beta3 involved in platelet adhesion and clot retraction and define the new recognition specificity of this integrin.