Mitchell C A, Jefferson A B, Bejeck B E, Brugge J S, Deuel T F, Majerus P W
Washington University School of Medicine, Division of Hematology-Oncology, St. Louis, MO.
Proc Natl Acad Sci U S A. 1990 Dec;87(23):9396-400. doi: 10.1073/pnas.87.23.9396.
Growth factors and transforming proteins that activate tyrosine phosphorylation have been shown to cause an increased labeling of 3-phosphate-containing phosphatidylinositols. Turnover correlates with the formation of a complex between phosphatidylinositol 3-kinase, the activated protein-tyrosine kinase, and other proteins thought to participate in transmembrane signaling. When human platelets are treated with thrombin, labeling of 3-phosphate-containing phosphatidylinositols is stimulated with a time course and concentration dependence consistent with a role for these lipids in platelet activation. We now report that when human platelets are stimulated with thrombin, a complex forms between phosphatidylinositol 3-kinase, a protein-serine/threonine kinase, and an uncharacterized platelet membrane protein. The complex is immunoprecipitated from detergent lysates of thrombinstimulated platelets by a rabbit antiserum prepared against a peptide from the cytoplasmic domain of the mouse platelet-derived growth factor (PDGF) receptor. The antigen is not the PDGF receptor, since complex formation is not stimulated by PDGF and thrombin-induced complexes are not precipitated by another rabbit antiserum against the same peptide or by monoclonal anti-human PDGF receptor antibodies. Formation of the complex is rapid (within 30 sec) and occurs at thrombin concentrations that stimulate platelet aggregation and secretion (50% of maximal complex formation at 0.03 unit of thrombin per ml). We propose that the complex initiates formation of 3-phosphate-containing phosphatidylinositols that may function in platelet activation.
已证实，激活酪氨酸磷酸化的生长因子和转化蛋白可使含3 - 磷酸的磷脂酰肌醇标记增加。其周转与磷脂酰肌醇3激酶、活化的蛋白酪氨酸激酶及其他参与跨膜信号传导的蛋白之间形成的复合物有关。当用人凝血酶处理人血小板时，含3 - 磷酸的磷脂酰肌醇标记受到刺激，其时间进程和浓度依赖性表明这些脂质在血小板激活中起作用。我们现在报道，当用人凝血酶刺激人血小板时，磷脂酰肌醇3激酶、一种蛋白丝氨酸/苏氨酸激酶与一种未鉴定的血小板膜蛋白之间形成复合物。该复合物可被一种兔抗血清从凝血酶刺激的血小板去污剂裂解物中免疫沉淀，该抗血清是针对小鼠血小板衍生生长因子（PDGF）受体胞质结构域的肽段制备的。抗原不是PDGF受体，因为PDGF不会刺激复合物形成，且凝血酶诱导的复合物不会被另一种针对相同肽段的兔抗血清或单克隆抗人PDGF受体抗体沉淀。复合物的形成迅速（在30秒内），且在刺激血小板聚集和分泌的凝血酶浓度下发生（每毫升0.03单位凝血酶时复合物形成达到最大值的50%）。我们提出，该复合物启动含3 - 磷酸的磷脂酰肌醇的形成，其可能在血小板激活中发挥作用。
