Kamada Yasuhiro, Yamada Yoichi, Yamakage Michiaki, Nagashima Masato, Tsutsuura Masaaki, Kobayashi Takeshi, Seki Sumihiko, Namiki Akiyoshi, Tohse Noritsugu
Department of Cellular Physiology and Signal Transduction, Sapporo Medical University School of Medicine, Sapporo, Hokkaido 060-8543, Japan.
Eur J Pharmacol. 2004 Mar 8;487(1-3):37-45. doi: 10.1016/j.ejphar.2004.01.016.
We recently cloned the beta(2c) subunit of the L-type Ca(2+) channel as a functional type of beta subunit from the rat heart. In order to clarify the contribution of the beta(2c) subunit to native Ca(2+) channel function, we investigated the single-channel properties of Ca(2+) channels reconstituted with beta(2a) or beta(2c) subunits and compared them with the properties of native channels. In contrast to the Ca(2+) channel with beta(2a) subunit, long-lasting closings were dominant in the Ca(2+) channel with beta(2c) subunit and the native channel. The ensemble-averaged current of the cells with beta(2c) subunits was comparable to that of the native cardiomyocytes. Many high P(o) sweeps (mode 2) were observed in the cells with beta(2a) subunits, while only a few high P(o) sweeps were observed in the cells with beta(2c) subunits and the native cells. These findings suggest that the beta(2c) subunit is one of the functional beta subunits in the rat heart.
我们最近从大鼠心脏中克隆出L型钙通道的β(2c)亚基，作为一种功能性β亚基类型。为了阐明β(2c)亚基对天然钙通道功能的贡献，我们研究了用β(2a)或β(2c)亚基重构的钙通道的单通道特性，并将其与天然通道的特性进行比较。与含有β(2a)亚基的钙通道不同，含有β(2c)亚基的钙通道和天然通道中，长时间关闭占主导。含有β(2c)亚基的细胞的整体平均电流与天然心肌细胞的相当。在含有β(2a)亚基的细胞中观察到许多高开放概率扫描（模式2），而在含有β(2c)亚基的细胞和天然细胞中仅观察到少数高开放概率扫描。这些发现表明β(2c)亚基是大鼠心脏中的功能性β亚基之一。
