Comparison of the properties of active Ca2+ transport by the islet-cell endoplasmic reticulum and plasma membrane.
Comparison of the properties of active Ca2+ transport by the islet-cell endoplasmic reticulum and plasma membrane.
复制标题
胰岛细胞内质网和质膜主动 Ca2 转运特性的比较。
DOI：
10.1016/0005-2736(83)90483-2
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
McDaniel,ML
中科院分区：
文献类型：
--
作者：
Colca,JR;Kotagal,N;Lacy,PE;McDaniel,ML
活性或ATP依赖性的胰岛细胞内质网和质膜富集的亚细胞组分的钙转运的属性进行了直接比较。这些研究表明，这两种膜的活性钙转运系统是根本不同的。与内质网富集部分的钙摄取相反，胰岛细胞质膜富集囊泡的钙摄取表现出不同的最佳pH值，不受草酸盐的影响，对离子钙的亲和力约为30倍。与这些胰岛细胞亚细胞组分相关的Ca 2+刺激的ATP酶活性表现出对钙的亲和力的类似差异。与钙调素对钙转运的影响一致，钙调素刺激质膜上的Ca 2 +-ATP酶，但不增加内质网膜上的钙刺激ATP酶活性。观察到的钙转运的内质网和质膜组分相对于胰岛素分泌的胰岛的调节的差异的生理意义进行了讨论。
The properties of active or ATP-dependent calcium transport by islet-cell endoplasmic reticulum and plasma membrane-enriched subcellular fractions were directly compared. These studies indicate that the active calcium transport systems of the two membranes are fundamentally distinct. In contrast to calcium uptake by the endoplasmic reticulum-enriched fraction, calcium uptake by islet-cell plasma membrane-enriched vesicles exhibited a different pH optimum, was not sustained by oxalate, and showed an approximate 30-fold greater affinity for ionized calcium. A similar difference in affinity for calcium was exhibited by the Ca2+-stimulated ATPase activities which are associated with these islet-cell subcellular fractions. Consistent with the effects of calmodulin on calcium transport, calmodulin stimulated Ca2+-ATPase in the plasma membranes, but did not increase calcium-stimulated ATPase activity in the endoplasmic reticulum membranes. The physiological significance of the differences observed in calcium transport by the endoplasmic reticulum and plasma membrane fractions relative to the regulation of insulin secretion by the islets of Langerhans is discussed.