Identification and subcellular localization of the subunits of L-type calcium channels and adenylyl cyclase in cardiac myocytes
Identification and subcellular localization of the subunits of L-type calcium channels and adenylyl cyclase in cardiac myocytes
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DOI：
10.1074/jbc.272.31.19401
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发表时间：
1997-08-01
影响因子：
4.8
通讯作者：
Hosey, MM
中科院分区：
文献类型：
--
作者：
Gao, TY;Puri, TS;Hosey, MM
心脏L-型钙通道的电生理特性已得到很好的表征，许多这类研究已证明该通道受cAMP依赖性途径的调节。然而，天然心脏L-型钙通道的亚基组成尚未完全确定。此外，关于成孔α（1）亚基的C-末端结构域的状态存在非常重要的问题，由于该结构域具有成为蛋白激酶靶点的潜力，但可能由于翻译后加工而被截短。在本研究中，α（1C）和β（2）亚基在从心脏膜部分纯化后，或从心肌细胞免疫沉淀后，通过亚基特异性抗体鉴定，发现β（2）和全长α（1C）亚单位均表达，并沿沿着T小管膜共定位于完整心肌细胞中。利用定量抗体结合分析，我们证明了在完整的心肌细胞中的大多数α（1C）亚基似乎是全长的。此外，我们观察到腺苷酸环化酶以类似于心肌细胞中通道亚基的模式定位。我们的研究结果为了解cAMP介导的信号通路对L型钙通道的调节提供了新的结构基础。
The properties of cardiac L-type channels have been well characterized electrophysiologically, and many such studies have demonstrated that the channels are regulated by a cAMP-dependent pathway, However, the subunit composition of native cardiac L-type calcium channels has not been completely defined, Furthermore, a very important question exists regarding the status of the C-terminal domain of the pore-forming alpha(1) subunit, as this domain has the potential to be the target of protein kinases but may be truncated as a result of posttranslational processing, In the present studies, the alpha(1C) and beta(2) subunits were identified by subunit-specific antibodies after partial purification from heart membranes, or immunoprecipitation from cardiac myocytes, Both the beta(2) and the full-length alpha(1C) subunits were found to be expressed and co-localized in intact cardiac myocytes along T-tubule membranes. Using a quantitative antibody binding analysis, we demonstrated that the majority of the alpha(1C) subunits in intact cardiac myocytes appear to be full-length, In addition, we observed that adenylyl cyclase is localized in a pattern similar to the channel subunits in cardiac myocytes, Taken together, our results provide new insights into the structural basis for understanding the regulation of L-type calcium channels by a cAMP-mediated signaling pathway.