Martin D W, Jesty J
Department of Medicine, State University of New York, Stony Brook 11794-8151, USA.
J Biol Chem. 1995 May 5;270(18):10468-74. doi: 10.1074/jbc.270.18.10468.
The human erythrocyte membrane is generally considered to have no procoagulant activity. The normal membrane is characterized as having an asymmetric distribution of phospholipid species such that negatively charged and aminophospholipids are predominantly located on the inner leaflet of the membrane bilayer. Elevation of cytoplasmic Ca2+ in erythrocytes produces an assortment of biochemical and structural responses that include diminished phospholipid asymmetry and an elevation in procoagulant activity. Maintenance of the normal asymmetric distribution of phospholipid species is believed to be largely mediated by a phospholipid translocase mechanism. We have utilized a recently developed single-step kinetic assay of procoagulant activity to investigate the mechanisms of Ca2+ stimulation of procoagulant activity and recovery from the procoagulant state upon removal of Ca2+. This study demonstrated that stimulation of procoagulant activity by elevated cytoplasmic Ca2+ is greatly diminished in ATP-depleted erythrocytes. Phospholipid translocase inhibitors failed to fully inhibit recovery from the procoagulant state after removal of Ca2+. The data indicate that recovery of endogenous lipid from a procoagulant cofiguration may not be entirely mediated by the phospholipid translocase. Additionally, the data are inconsistent with the phospholipid translocase mediating the Ca(2+)-induced elevation of procoagulant activity, although the involvement of other protein(s) is indicated.
一般认为人类红细胞膜没有促凝活性。正常膜的特征是磷脂种类呈不对称分布，使得带负电荷的磷脂和氨基磷脂主要位于膜双层的内小叶。红细胞胞质Ca2+升高会产生一系列生化和结构反应，包括磷脂不对称性降低和促凝活性升高。磷脂种类正常不对称分布的维持在很大程度上被认为是由磷脂转位酶机制介导的。我们利用最近开发的促凝活性单步动力学测定法来研究Ca2+刺激促凝活性的机制以及去除Ca2+后从促凝状态恢复的机制。这项研究表明，在ATP耗尽的红细胞中，胞质Ca2+升高对促凝活性的刺激作用大大减弱。磷脂转位酶抑制剂未能完全抑制去除Ca2+后从促凝状态的恢复。数据表明，从促凝构型恢复内源性脂质可能并非完全由磷脂转位酶介导。此外，尽管表明有其他蛋白质参与，但数据与磷脂转位酶介导Ca(2+)诱导的促凝活性升高不一致。
