The Ca2+/calmodulin binding domain of the Ca2+‐ATPase linked to the Na+,K+‐ATPase alters transport stoichiometry

FEBS Letters

Yoshimura, Shige H.¹  Schwarz, Wolfgang¹  Ishii, Toshiaki³  Gu, Quanbao¹  Zhao, Jianxing¹  Vasilets, Larisa A.¹  Takeyasu, Kunio² 

[1] Max-Planck Institut für Biophysik, Kennedyallee 70, D-60596 Frankfurt/Main, Germany;Neurobiotechnology Center, Ohio State University, Columbus, OH 43210-1002, USA;Research Institute for Advances in Science and Technology, University of Osaka Prefecture, Osaka 591, Japan

关键词: Sodium pump;    Alpha-subunit;    Beta-subunit;    Calmodulin;    Ion (Na+) transport;    Electrogenicity;   

DOI  :  10.1016/S0014-5793(97)00435-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Using Xenopus oocytes as an expression system, we have investigated ion-transport and ouabain-binding properties of a chimeric ATPase (α₁-CBD; Ishii and Takeyasu (1995) EMBO J. 14, 58–67) formed by the α₁-subunit of chicken Na⁺,K⁺-ATPase (α₁) and the calmodulin binding domain (CBD) of the rat plasma membrane Ca²⁺-ATPase. α₁-CBD can be expressed and transported to the oocyte plasma membrane without the β-subunit, and shows ouabain binding. In contrast to ouabain binding, this chimera requires the β-subunit for its cation (Na⁺ and K⁺) transport activity. α₁-CBD exhibits an altered stoichiometry of Na⁺-K⁺ exchange. A detailed analysis of ²²Na⁺ efflux, ⁸⁶Rb⁺ uptake, pump current and ouabain binding suggests that the chimeric molecule can operate in an electrically silent 2Na⁺–2K⁺ exchange mode and, with much lower probability, in its normal 3Na⁺–2K⁺ exchange mode.

【 授权许可】

Unknown