Role of S5-S6 regions of the subunits in inactivation of Kv1.4/Kv1.2 hybrid channel

• Published in: Japanese Journal of Pharmacology Vol. 73; no. suppl.1; p. 190
• Main Authors: Nunoki, Kazuo, Hashimoto, Yoshihiro
• Format: Journal Article
• Language: English; Japanese
• Published: The Japanese Pharmacological Society 1997
• ISSN: 0021-5198; 1347-3506
• DOI: 10.1016/S0021-5198(19)45261-X

We have previously reported that the hybrid channel can be encoded by the fusion genes of Kv1.4 and Kv1.2. In that study, it has been elucidated that the current of the hybrid channel is quite similar to I_10 , which is observed in the cardiac muscle. It is also indicated that the Kv1.2 subunit, which does not contain the structure of "inactivating ball", plays a role in inactivation of the hybrid channel. We have suggested that all of the S4-S5 loops derived from each subunit contribute to the inactivation of the hybrid channel as the acceptor site for the inactivating ball. In this study, the role of the S5-S6 regions of Kv1.4 and Kv1.2 subunits in inactivation was examined. The fusion genes encoding the hybrid channels were constracted, in which the S5-S6 region of Kv1.4 or Kv1.2 component was replaced with the corresponding region of Kv1.2 or Kv1.4, or the S5-S6 regions were interchanged between the two components. These genes were expressed in Xenopus oocytes. Electrophysiological characteristics of the expressed channels is under investigation by two-microelectrode voltage clamp. We will present the data on how inactivation of the hybrid channels is modified by replacing the S5-S6 regions of the subunits.