Structural diversity of L-type Ca^<2+> channel in sinoatrial node-the possibility of Cav-Cav interaction-

在本研究中，我们检测了Cav1.2和Cav1.3亚基功能性组装产生持续性内向Na^+电流（I_）的可能性<st>，I_是窦房结的起搏电流。Cav1.2和Cav1.3在HEK细胞中的异源共表达导致了归因于每个Cav通道的Ca^2+电流集合。另一方面，由来自Cav1.2（或Cav1.3）的重复序列I和II以及来自Cav1.3（或Cav1.2）的重复序列III和IV组成的嵌合通道可引起快速失活的Ca^2+电流，但不能引起类似于I的Na^+电流<st>。综上所述，这是不可能的，Cav1.2和Cav1.3亚基的异聚体组装的基础，在窦房结I_<st>。

In the present study, we examined the possibility of the functional assembly of Cav1.2 and Cav1.3 subunits to yield the sustained inward Na^+ current (I_<st>), a pacemaker current in sinoatrial node. Heterologous coexpression of Cav1.2 and Cav1.3 in HEK cells resulted in an ensemble of Ca^<2+> currents attributed to each Cav channel. On the other hand, the chimeric channel consisting of repeat I and II from Cav1.2 (or Cav1.3) and repeat III and IV from Cav1.3 (or Cav1.2) elicited a rapidly inactivating Ca^<2+> current but failed to evoke a Na^+ current similar to I_<st>. Taken together, it is not likely that the heteromeric assembly of Cav1.2 and Cav1.3 subunits underlies I_<st> in sinoatrial node.