NORMALIZATION OF CURRENT KINETICS BY INTERACTION BETWEEN THE ALPHA-1-SUBUNIT AND BETA-SUBUNIT OF THE SKELETAL-MUSCLE DIHYDROPYRIDINE-SENSITIVE CA2+ CHANNEL
NORMALIZATION OF CURRENT KINETICS BY INTERACTION BETWEEN THE ALPHA-1-SUBUNIT AND BETA-SUBUNIT OF THE SKELETAL-MUSCLE DIHYDROPYRIDINE-SENSITIVE CA2+ CHANNEL
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DOI：
10.1038/352527a0
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发表时间：
1991-08-08
期刊：
影响因子：
64.8
通讯作者：
BROWN, AM
中科院分区：
文献类型：
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作者：
LACERDA, AE;KIM, HS;BROWN, AM
骨骼肌二氢吡啶结合位点的纯化使蛋白质复合物能够被分离，从该蛋白质复合物中已经重建了Ca 2+电流。编码二氢吡啶受体的五个亚基α-1、β、γ、α-2和δ（参考文献1）的互补DNA已被克隆2-6，现在认识到α-2和δ衍生自共同的前体7，8。 α-1亚基本身可以产生Ca 2+电流，正如使用缺乏α-2-δ（参考文献9，10），β（参考文献10）和γ（我们未发表的结果）的小鼠L细胞所证明的那样。在L细胞中，单独稳定表达骨骼肌-α-1足以产生电压敏感的、高阈值的L型钙通道电流，该电流是二氢吡啶敏感的并被Cd 2+阻断，但激活动力学比骨骼肌钙通道电流预期的慢约100倍。这可能是由于表达α-1的细胞类型或缺乏调节成分，特别是与α-1共纯化的亚基之一。我们在这里显示，骨骼肌-β与骨骼肌-α-1的共表达产生表达具有正常激活动力学的Ca 2+通道电流的细胞系，作为二氢吡啶受体β亚基参与骨骼肌Ca 2+通道电流产生的证据。
PURIFICATION of skeletal muscle dihydropyridine binding sites has enabled protein complexes to be isolated from which Ca2+ currents have been reconstituted. Complementary DNAs encoding the five subunits of the dihydropyridine receptor, alpha-1, beta, gamma, alpha-2 and delta (ref. 1), have been cloned 2-6 and it is now recognized that alpha-2 and delta are derived from a common precursor 7,8. The alpha-1 subunit can itself produce Ca2+ currents, as was demonstrated using mouse L cells lacking alpha-2-delta (refs 9, 10), beta (ref. 10) and gamma (our unpublished results). In L cells, stable expression of skeletal muscle-alpha-1 alone was sufficient to generate voltage-sensitive, high-threshold L-type Ca2+ channel currents which were dihydropyridine-sensitive and blocked by Cd2+, but the activation kinetics were about 100 times slower than expected for skeletal muscle Ca2+ channel currents. This could have been due to the cell type in which alpha-1 was being expressed or to the lack of a regulatory component particularly one of the subunits that copurifies with alpha-1. We show here that coexpression of skeletal muscle-beta with skeletal muscle-alpha-1 generates cell lines expressing Ca2+ channel currents with normal activation kinetics as evidence for the participation of the dihydropyridine-receptor beta-subunits in the generation of skeletal muscle Ca2+ channel currents.