Studies on sickled erythrocytes provide evidence that the asymmetric distribution of phosphatidylserine in the red cell membrane is maintained by both ATP-dependent translocation and interaction with membrane skeletal proteins.
Studies on sickled erythrocytes provide evidence that the asymmetric distribution of phosphatidylserine in the red cell membrane is maintained by both ATP-dependent translocation and interaction with membrane skeletal proteins.
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对镰状红细胞的研究提供的证据表明，红细胞膜中磷脂酰丝氨酸的不对称分布是通过 ATP 依赖性易位和与膜骨架蛋白的相互作用维持的。
DOI：
10.1016/0005-2736(88)90250-7
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
Roelofsen,B
中科院分区：
文献类型：
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作者：
Middelkoop,E;Lubin,BH;Bevers,EM;OpdenKamp,JA;Comfurius,P;Chiu,DT;Zwaal,RF;vanDeenen,LL;Roelofsen,B
为了研究参与维持人红细胞内磷脂酰丝氨酸（PS）不对称的因素，我们测量了镰状细胞诱导的atp耗竭和膜骨架/脂双分子层解耦对镰状细胞内磷脂酰丝氨酸分布的影响。使用从牛肝脏纯化的非特异性脂质转移蛋白，将微量放射性标记的PS引入新鲜和atp耗尽的可逆镰状细胞（RSCs）的外膜小叶中。新引入的PS在两半双分子层上的平衡是通过磷脂酶a2处理细胞来监测的，磷脂酶a2选择性地水解那些存在于外膜小叶中的分子。在插入新鲜的RSCs后1小时内，只有10%的标记PS可以被磷脂酶A2作用。当细胞随后缺氧时，这一比例明显增加。在加入放射性标记的PS后，被剥夺ATP的RSCs延长脱氧时间，导致磷脂酶a2诱导的放射性标记PS的水解增强。同样，当ATP缺失时，完整RSCs中磷脂酶a2诱导的内源性PS的水解明显增强，而新鲜细胞在氮气下孵育3.5小时时则没有。凝血酶原和Ca2+这种增强似乎取决于在氮下孵育的时间。这一现象表明外膜小叶中内源性PS的数量在增加，而新鲜的RSCs或atp耗尽的正常红细胞在氮气下孵育时都没有观察到。我们目前的观察结果提供了证据，除了PS与骨骼蛋白的相互作用外，PS的atp依赖性易位需要维持其在人红细胞膜中的绝对不对称分布。
In order to study factors which are involved in maintenance of phosphatidylserine (PS) asymmetry within the human red cell membrane, we measured the effect of ATP-depletion and of membrane skeleton/lipid bilayer uncoupling induced by sickling on the distribution of PS within the membrane bilayer of sickle cells. Trace amounts of radiolabeled PS were introduced into the outer membrane leaflet of both fresh and ATP-depleted reversibly sickled cells (RSCs), using a non-specific lipid transfer protein purified from bovine liver. The equilibration of the newly introduced PS over the two halves of the bilayer was monitored by treatment of the cells with phospholipase A2which selectively hydrolyzes only those molecules present in the outer membrane leaflet. Within 1 h after insertion into fresh RSCs, only 10% of the labeled PS was accessible to the action of phospholipase A2. This fraction was markedly increased when the cells were subsequently deoxygenated. Prolonged deoxygenation of RSCs, deprived of their ATP after incorporation of radiolabeled PS, caused enhanced phospholipase A2-induced hydrolysis of radiolabeled PS. Similarly, phospholipase A2-induced hydrolysis of endogenous PS in intact RSCs was markedly enhanced when ATP-depleted, but not when fresh cells, were incubated under nitrogen for 3.5 h. Deoxygenated ATP-depleted RSCs markedly enhanced the rate of thrombin formation in the presence of purified coagulation factors Xa, Va, prothrombin and Ca2+. This enhancement appeared to be dependent on the duration of incubation under nitrogen. This phenomenon, indicating the presence of increasing amounts of endogenous PS in the outer membrane leaflet, was not observed when either fresh RSCs or ATP-depleted normal erythrocytes were incubated under nitrogen. Our present observations provide evidence that, in addition to the interaction of PS with the skeletal proteins, an ATP-dependent translocation of PS is required to maintain its absolute asymmetric distribution in the human erythrocyte membrane.