Weiner M L, Lee K S
J Gen Physiol. 1972 Apr;59(4):462-75. doi: 10.1085/jgp.59.4.462.
The relationship between active extrusion of Ca(++) from red cell ghosts and active uptake of Ca(++) by isolated red cell membrane fragments was investigated by studying the Ca(++) uptake activities of inside-out and right side-out vesicles. Preparations A and B which had mainly inside-out and right side-out vesicles, respectively, were isolated from red cell membranes and were compared with respect to Ca(++) adenosine triphosphatase (ATPase) and ATP-dependent Ca(++) uptake activities. Preparation A had nearly eight times more inside-out vesicles and took up eight times more (45)Ca in the presence of ATP compared to preparation B. Separation of the (45)Ca-labeled membrane vesicles by density gradient centrifugation showed that the (45)Ca label was localized to the inside-out vesicle fraction. In addition, the (45)Ca taken up in the presence of ATP was lost during a subsequent incubation in the absence of ATP. The rate of (45)Ca loss was not influenced by the presence of EGTA, but was slowed in the presence of La(+8) (0.1 mM) in the efflux medium. The results presented here support the thesis that the active uptake of Ca(++) by red cell membrane fragments is due to the active transport of Ca(++) into inside-out vesicles.
通过研究外翻囊泡和正常取向囊泡的钙离子摄取活性，对红细胞血影中钙离子的主动外排与分离的红细胞膜片段对钙离子的主动摄取之间的关系进行了研究。分别主要由外翻囊泡和正常取向囊泡组成的制剂A和制剂B从红细胞膜中分离出来，并就钙离子腺苷三磷酸酶（ATP酶）和ATP依赖的钙离子摄取活性进行了比较。与制剂B相比，制剂A的外翻囊泡数量几乎多八倍，并且在ATP存在的情况下摄取的（45）钙多八倍。通过密度梯度离心分离（45）钙标记的膜囊泡表明，（45）钙标记定位于外翻囊泡部分。此外，在ATP存在下摄取的（45）钙在随后无ATP的孵育过程中丢失。（45）钙的丢失速率不受EGTA存在的影响，但在流出培养基中存在镧（+8）（0.1 mM）时会减慢。此处给出的结果支持以下论点：红细胞膜片段对钙离子的主动摄取是由于钙离子主动转运到外翻囊泡中。
