Morton M E, Froehner S C
Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03756.
Neuron. 1989 May;2(5):1499-506. doi: 10.1016/0896-6273(89)90196-7.
The dihydropyridine (DHP) binding complex isolated from skeletal muscle contains two large proteins, alpha 1 and alpha 2, and at least two smaller polypeptides. The alpha 1 subunit has a primary structure expected for ion channels and is a functional component of a DHP-sensitive, voltage-activated calcium channel. The functions of the alpha 2 protein and the smaller polypeptides are unknown. We prepared monoclonal antibodies to the alpha 1 and alpha 2 polypeptides and studied the developmental appearance and tissue distribution of these two proteins. In rat skeletal muscle, the levels of alpha 1 are quite low during the first 10 days after birth, then rise dramatically, and, by day 20, approach those found in adult muscle. In direct contrast, alpha 2 is present in substantial amounts in rat muscle at birth and increases only slightly during this same period of development. Furthermore, alpha 1 is detected only in skeletal muscle, whereas alpha 2 is present in a variety of tissues. These results provide evidence for the segregation of these two polypeptides and suggest that the function of alpha 2 is not limited to that associated with the DHP-sensitive calcium channel.
从骨骼肌中分离出的二氢吡啶（DHP）结合复合物包含两种大蛋白，α1和α2，以及至少两种较小的多肽。α1亚基具有离子通道预期的一级结构，是DHP敏感的电压激活钙通道的功能成分。α2蛋白和较小多肽的功能尚不清楚。我们制备了针对α1和α2多肽的单克隆抗体，并研究了这两种蛋白的发育出现情况和组织分布。在大鼠骨骼肌中，α1的水平在出生后的前10天相当低，然后急剧上升，到第20天时，接近成年肌肉中的水平。与之形成直接对比的是，α2在大鼠肌肉出生时大量存在，在同一发育时期仅略有增加。此外，α1仅在骨骼肌中被检测到，而α2存在于多种组织中。这些结果为这两种多肽的分离提供了证据，并表明α2的功能不限于与DHP敏感钙通道相关的功能。
