Dorahy D J, Burns G F
Cancer Research Unit, Faculty of Medicine and Health Sciences, University of Newcastle, Callaghan, 2308 NSW, Australia.
Biochem J. 1998 Jul 15;333 ( Pt 2)(Pt 2):373-9. doi: 10.1042/bj3330373.
Circulating platelets are primed to respond very rapidly to thrombogenic stimuli, but most platelets complete their lifespan without ever becoming activated. Platelet activation is accompanied by waves of sequential tyrosine phosphorylation thought to involve members of the Src family of protein tyrosine kinases (PTKs). We show here that resting platelets contain highly active pp53/56(Lyn) PTK within membrane microdomains (rafts) isolated biochemically with or without the use of detergent. This fraction is also greatly enriched in the transmembrane glycoprotein CD36, known to associate with Lyn PTK, but in transfection studies we could find no evidence to suggest that CD36 affects the distribution or function of Lyn. Upon platelet activation Lyn activity remains constant or diminishes and pp60(c-src) PTK within this fraction becomes highly activated, indicating the dynamic nature of the membrane microdomains. It is suggested that the function of active Lyn PTK in the resting platelet is to allow prolonged survival of this anucleate cell.
循环血小板已做好准备,能对血栓形成刺激做出非常快速的反应,但大多数血小板在未被激活的情况下度过其生命周期。血小板激活伴随着一系列酪氨酸磷酸化浪潮,这些磷酸化被认为涉及蛋白酪氨酸激酶(PTK)的Src家族成员。我们在此表明,静息血小板在使用或不使用去污剂进行生化分离的膜微结构域(筏)中含有高活性的pp53/56(Lyn)PTK。该部分还富含跨膜糖蛋白CD36,已知其与Lyn PTK相关,但在转染研究中,我们没有发现证据表明CD36会影响Lyn的分布或功能。血小板激活后,Lyn活性保持恒定或降低,该部分中的pp60(c-src)PTK则变得高度激活,这表明膜微结构域具有动态特性。有人认为,静息血小板中活性Lyn PTK的功能是使这种无核细胞得以长期存活。