Calcium pump of the plasma membrane is localized in caveolae.
Calcium pump of the plasma membrane is localized in caveolae.
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DOI：
10.1083/jcb.120.5.1147
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发表时间：
1993-03
期刊：
影响因子：
--
通讯作者：
Fujimoto T
中科院分区：
文献类型：
--
作者：
Fujimoto T
质膜上的钙泵在细胞质内游离钙离子浓度的精细调控中起着关键作用。在本研究中，使用针对红细胞膜Ca~(2+)泵ATPase的特异性抗体，用免疫细胞化学技术检测其亚细胞定位。在培养细胞的免疫荧光显微镜下，抗体的标记显示为许多小点，通常呈线状排列或沿细胞边缘分布。冰冻切片的免疫金电镜显示，这些斑点对应于质膜上光滑的凹陷。应用于小鼠体内组织的相同技术表明，钙泵类似地定位于内皮细胞、平滑肌细胞、心肌细胞、表皮角质形成细胞和间皮细胞的小窝中。免疫金标记法定量分析发现，毛细血管内皮细胞和内脏平滑肌细胞的钙泵在肺泡膜上的浓度是质膜上非肺泡部的18-25倍。在肾小管和小肠上皮细胞中，已知含有钙泵，但小凹不多，大多数标记随机分布在基底侧质膜上，尽管小窝也呈阳性标记。结果表明，不同细胞内的小凹具有共同的组成成分--质膜钙泵。结合我们最近的发现，在小窝(Fujimoto，T.，S.Nakade，A.Miywaki，K.Mikoshiba和K.Ogawa)中存在一个肌醇1，4，5-三磷酸受体样蛋白。1992年。J.细胞生物学。119：1507-1513)，推测光滑的质膜内陷是一种专用于钙离子从细胞质中摄取和排出的器官。
The Ca2+ pump in the plasma membrane plays a key role in the fine control of the cytoplasmic free Ca2+ concentration. In the present study, its subcellular localization was examined with immunocytochemical techniques using a specific antibody generated against the erythrocyte membrane Ca2+ pump ATPase. By immunofluorescence microscopy of cultured cells, the labeling with the antibody was seen as numerous small dots, often distributed in linear arrays or along cell edges. Immunogold EM of cryosections revealed that the dots correspond to caveolae, or smooth invaginations of the plasma membrane. The same technique applied to mouse tissues in vivo showed that the Ca2+ pump is similarly localized in caveolae of endothelial cells, smooth muscle cells, cardiac muscle cells, epidermal keratinocytes and mesothelial cells. By quantitative analysis of the immunogold labeling, the Ca2+ pump in capillary endothelial cells and visceral smooth muscle cells was found to be concentrated 18-25-fold in the caveolar membrane compared with the noncaveolar portion of the plasma membrane. In renal tubular and small intestinal epithelial cells, which have been known to contain the Ca2+ pump but do not have many caveolae, most of the labeling was randomly distributed in the basolateral plasma membrane, although caveolae were also positively labeled. The results demonstrate that the caveolae in various cells has the plasmalemmal Ca2+ pump as a common constituent. In conjunction with our recent finding that an inositol 1,4,5-trisphosphate receptor-like protein exists in the caveolae (Fujimoto, T., S. Nakade, A. Miyawaki, K. Mikoshiba, and K. Ogawa. 1992. J. Cell Biol. 119:1507-1513), it is inferred that the smooth plasmalemmal invagination is an apparatus specialized for Ca2+ intake and extrusion from the cytoplasm.