Recognition of Fibronectin by the Platelet Integrin IIb
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- 作者：Adam C. W. Kauf ; Scott M. Hough ; and Ron D. Bowditch
- 刊名：Biochemistry
- 出版年：2001
- 出版时间：August 7, 2001
- 年：2001
- 卷：40
- 期：31
- 页码：9159 - 9166
- 全文大小：257K
- 年卷期：v.40,no.31(August 7, 2001)
- ISSN：1520-4995
文摘
Normal platelet function is dependent on the ability of integrin 
IIb
3 (glycoprotein IIb/IIIa)to interact with components of the subendothelial matrix, such as fibronectin (Fn), exposed at sites ofvascular injury. Studies using synthetic peptides derived from human Fn sequences Asp1373-Thr1383 andArg1493-Asp1495 have suggested a role for both the 9th (3fn9) and 10th (3fn10) type III repeats of thisligand in binding to IIb3. In this study, we have taken a charge-to-alanine mutagenesis approach toevaluate the importance of these sites, and other charged residues, within the context of recombinant3fn9-10 modules for binding to IIb3. To identify residues that are involved in Fn binding to IIb3,recombinantly expressed 3fn9-10 module pairs with alanine substitutions introduced into each of the 38charged residues were individually assayed for the ability to inhibit Fn binding to purified IIb3.Substitutions at Fn residues Arg1493 and Asp1495 of the RGD sequence were found to have the greatesteffect on IIb3 binding, as expected. However, Fn residues Arg1369, Arg1371, Arg1379, Arg1445, and Arg1448were needed for optimal interaction of the 3fn9-10 module pair with IIb3. All Fn residues found toaffect binding of 3fn9-10 to IIb3 are located on the same face and extend from the surface of themolecule. Additionally, the epitopes for two anti-Fn monoclonal antibodies that inhibit binding of thisligand to IIb3 were found to overlap the sites identified. These results demonstrate that IIb3-Fnbinding involves multiple electrostatic interactions.
IIb3 (glycoprotein IIb/IIIa)to interact with components of the subendothelial matrix, such as fibronectin (Fn), exposed at sites ofvascular injury. Studies using synthetic peptides derived from human Fn sequences Asp1373-Thr1383 andArg1493-Asp1495 have suggested a role for both the 9th (3fn9) and 10th (3fn10) type III repeats of thisligand in binding to IIb3. In this study, we have taken a charge-to-alanine mutagenesis approach toevaluate the importance of these sites, and other charged residues, within the context of recombinant3fn9-10 modules for binding to IIb3. To identify residues that are involved in Fn binding to IIb3,recombinantly expressed 3fn9-10 module pairs with alanine substitutions introduced into each of the 38charged residues were individually assayed for the ability to inhibit Fn binding to purified IIb3.Substitutions at Fn residues Arg1493 and Asp1495 of the RGD sequence were found to have the greatesteffect on IIb3 binding, as expected. However, Fn residues Arg1369, Arg1371, Arg1379, Arg1445, and Arg1448were needed for optimal interaction of the 3fn9-10 module pair with IIb3. All Fn residues found toaffect binding of 3fn9-10 to IIb3 are located on the same face and extend from the surface of themolecule. Additionally, the epitopes for two anti-Fn monoclonal antibodies that inhibit binding of thisligand to IIb3 were found to overlap the sites identified. These results demonstrate that IIb3-Fnbinding involves multiple electrostatic interactions.