Thromb Haemost 1998; 80(02): 310-315
DOI: 10.1055/s-0037-1615193
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Characteristics of the Interaction between Thrombin Exosite1 and the Sequence 269-297 of Platelet Glycoprotein Ibα[*]

Marie-Christine Bouton
1  Laboratoire de Recherche sur l‘Hémostase et la Thrombose, Faculté de Médecine Xavier Bichat, Paris, France
,
Christophe Thurieau
2  Laboratoires de Recherche Servier, Suresnes, France
,
Marie-Claude Guillin
1  Laboratoire de Recherche sur l‘Hémostase et la Thrombose, Faculté de Médecine Xavier Bichat, Paris, France
,
Martine Jandrot-Perrus
1  Laboratoire de Recherche sur l‘Hémostase et la Thrombose, Faculté de Médecine Xavier Bichat, Paris, France
› Author Affiliations
Further Information

Publication History

Received 14 October 1997

Accepted after resubmission 09 April 1998

Publication Date:
27 December 2017 (online)

Summary

The interaction between GPIb and thrombin promotes platelet activation elicited via the hydrolysis of the thrombin receptor and involves structures located on the segment 238-290 within the N-terminal domain of GPIbα and the positively charged exosite 1 on thrombin. We have investigated the ability of peptides derived from the 269-287 sequence of GPIbα to interact with thrombin. Three peptides were synthesized, including Ibα 269-287 and two scrambled peptides R1 and R2 which are comparable to Ibα 269-287 with regards to their content and distribution of anionic residues. However, R2 differs from both Ibα 269-287 and R1 by the shifting of one proline from a central position to the N-terminus. By chemical cross-linking, we observed the formation of a complex between 125I-Ibα 269-287 and α-thrombin that was inhibited by hirudin, the C-terminal peptide of hirudin, sodium pyrophosphate but not by heparin. The complex did not form when γ-thrombin was substituted for α-thrombin. Ibα 269-287 produced only slight changes in thrombin amidolytic activity and inhibited thrombin binding to fibrin. R1 and R2 also formed complexes with α-thrombin, modified slightly its catalytic activity and inhibited its binding to fibrin. Peptides Ibα 269-287 and R1 inhibited platelet aggregation and secretion induced by low thrombin concentrations whereas R2 was without effect. Our results indicate that Ibα 269-287 interacts with thrombin exosite 1 via mainly electrostatic interactions, which explains why the scrambled peptides also interact with exosite 1. Nevertheless, the lack of effect of R2 on thrombin-induced platelet activation suggests that proline 280 is important for thrombin interaction with GPIb.

* This work was supported by grants from the European Community (Biomed 2, Contract BMH4-CT96-0937), the MENESR (ACC-SV9) and Université Paris 7. Preliminary accounts of this work were presented at the XVIth Congress of the International Society on Thrombosis and Haemostasis, June, 1997, Florence, Italy and published in an abstract form (Bouton MC, Thurieau C, Guillin MC, Jandrot-Perrus M, Thromb Haemost 1997, Suppl, 604a)