Karczewski J, Connolly T M
Department of Pharmacology, Merck Research Laboratories, West Point, Pennsylvania 19486, USA.
Biochem Biophys Res Commun. 1997 Dec 29;241(3):744-8. doi: 10.1006/bbrc.1997.7881.
Disagregin, a 6 kDa protein isolated from salivary glands of the tick Ornithodoros Moubata, is a potent and selective inhibitor of fibrinogen dependent platelet aggregation and of the adhesion of platelets to fibrinogen (Karczewski et al. (1994) J. Biol. Chem. 269, 6702-6708). In the current study the interaction of disagregin with purified glycoprotein IIb-IIIa (GPIIb-IIIa) was examined. Biotin-labeled disagregin (b-disagregin) bound to GPIIb-IIIa immobilized on the surface of the ELISA plate. This binding was specific, dependent on divalent cations, and was blocked by the peptides fibrinogen gamma-chain fg gamma (400-411), GPIIb(296-306) and by the RGD-containing peptide, GRGDSP. Disagregin also bound to soluble GPIIb-IIIa as demonstrated in studies using the chemical crosslinker, BS3. This binding was inhibited by the peptides fg gamma (400-411) and GPIIb(296-306). In contrast to the results in the solid phase, peptide GRGDSP had no effect on the binding of b-disagregin to soluble GPIIb-IIIa. These data demonstrate that disagregin binds to GPIIb-IIIa through a mechanism distinct from that used by RGD-containing disintegrins. Further analysis of the region(s) of disagregin which bind to GPIIb-IIIa should provide useful information for molecular modeling of the fibrinogen binding site on GPIIb-IIIa and for the design of a new class of potent fibrinogen receptor antagonists.
去整合素是一种从钝缘蜱唾液腺中分离出的6 kDa蛋白质，是纤维蛋白原依赖性血小板聚集以及血小板与纤维蛋白原黏附的强效选择性抑制剂（Karczewski等人，（1994年）《生物化学杂志》269卷，6702 - 6708页）。在当前研究中，对去整合素与纯化的糖蛋白IIb - IIIa（GPIIb - IIIa）的相互作用进行了检测。生物素标记的去整合素（b - 去整合素）与固定在酶联免疫吸附测定（ELISA）板表面的GPIIb - IIIa结合。这种结合具有特异性，依赖于二价阳离子，并被纤维蛋白原γ链fgγ（400 - 411）肽、GPIIb（296 - 306）肽以及含RGD的肽GRGDSP所阻断。去整合素也与可溶性GPIIb - IIIa结合，这在使用化学交联剂BS3的研究中得到了证实。这种结合被fgγ（400 - 411）肽和GPIIb（296 - 306）肽所抑制。与固相结果相反，肽GRGDSP对b - 去整合素与可溶性GPIIb - IIIa的结合没有影响。这些数据表明，去整合素通过一种不同于含RGD去整合素的机制与GPIIb - IIIa结合。对去整合素中与GPIIb - IIIa结合区域的进一步分析，应为GPIIb - IIIa上纤维蛋白原结合位点的分子建模以及新型强效纤维蛋白原受体拮抗剂的设计提供有用信息。
