A new interaction between proximal and distal C-terminus of Cav1.2 channels
A new interaction between proximal and distal C-terminus of Cav1.2 channels
复制标题
Cav1.2通道近端和远端C端之间的新相互作用
DOI：
10.1016/j.jphs.2017.03.002
复制
发表时间：
2017
影响因子：
3.5
通讯作者：
Kameyama Masaki
中科院分区：
文献类型：
--
作者：
Lyu Liting;Gao Qinghua;Xu Jianjun;Minobe Etsuko;Zhu Tong;Kameyama Masaki
心脏Cav1.2通道是一种将细胞膜刺激与细胞内Ca ~（2+）信号传导相耦合的通道，受多种胞质因子如钙调蛋白（CaM）、磷酸化、Ca ~（2+）、ATP和通道分子内片段的调节。Cav1.2通道的远端和近端C端调控结构域（DCRD和PCRD）之间的相互作用抑制了通道活性，而PKA介导的磷酸化通过释放这种相互作用促进了Cav1.2通道的活性。在这里，我们报告的远端C-末端（CT 3）和近端C-末端（CT 1）之间的相互作用被抑制钙调素在钙离子依赖的方式。此外，CT 3D（DCRD截短的短CT 3）与CT 1B（EF-手和PCRD截短的短CT 1）相互作用，揭示了远端和近端C-末端之间的新相互作用。Ca 2 +/CaM对CT 3D与CT 1B结合的抑制作用强于CT 3与CT 1的结合，提示CT 3/CT 1中DCRD/PCRD的相互作用可能与CT 3D与CT 1B的结合有协同作用。我们将CT 3D的新CT 1B结合区命名为CaM竞争结构域（CCD）。电生理实验表明，CT 3D抑制而CT 1B易化豚鼠心室肌细胞内面朝外斑片Cav1.2通道活动。这些结果表明，远端C端抑制Cav1.2通道通过调节通道的钙调蛋白结合特性。
Cardiac Cav1.2 channels, coupling membrane stimulation to intracellular Ca2+signaling, are regulated by multiple cytoplasmic factors, such as calmodulin (CaM), phosphorylation, Ca2+, ATP and intramolecular fragments of the channel. The interaction between distal and proximal C-terminal regulatory domains (DCRD and PCRD) of Cav1.2 channel is suggested to inhibit the channel activity, while PKA-mediated phosphorylation facilitates Cav1.2 channel by releasing such an interaction. Here, we report that the interaction between the distal C-terminus (CT3) and the proximal C-terminus (CT1) are inhibited by CaM in a Ca2+-dependent manner. Furthermore, CT3D (a short CT3 with DCRD truncated) interacts with CT1B (a short CT1 with EF-hand and PCRD truncated), revealing a new interaction between distal and proximal C-terminus. Ca2+/CaM inhibited the binding of CT3D to CT1B more strongly than the binding between CT3 and CT1, implying that the interaction of DCRD/PCRD (in CT3/CT1) might cooperate with the binding of CT3D to CT1B. We name the new CT1B-binding region of CT3D as CaM-competitive domain (CCD). The electrophysiological experiments show that CT3D inhibits while CT1B facilitates Cav1.2 channel activity in inside-out patches in guinea-pig ventricular myocytes. These results suggest that distal C-terminus inhibits Cav1.2 channel through modulation of the CaM-binding property of the channels.