Voltage‐dependent pump currents of the sarcoplasmic reticulum Ca2+‐ATPase in planar lipid membranes

FEBS Letters

Bamberg, Ernst¹  Eisenrauch, Andreas¹ 

[1] Max-Planck-Institut für Biophysik, Kennedyallee 70, D-6000 Frankfurt am Main 70, FRG

关键词: Ca2+-ATPase;    Sarcoplasmic reticulum;    Reconstitution;    Planar lipid membrane;    Voltage dependence;    Caged ATP;   

DOI  :  10.1016/0014-5793(90)80996-V

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Sarcoplasmic reticulum vesicles containing largely Ca²⁺-ATPase were incorporated into planar lipid membranes. The ATPase was activated by a UV flash-induced concentration jump of ATP from a photolabile caged ATP. Under these conditions stationary pump currents were observed. The dependence of these pump currents on applied voltages was investigated. The current-voltage curve of the Ca²⁺-ATPase shows monotonously increasing pump currents with increasing positive potentials of the ATP containing compartment. This indicates the existence of electrogenic steps in the direction of the transported Ca²⁺ ions. From the extrapolated reversal potentials of the curve is concluded that less than four positive net charges are transported per hydrolyzed ATP.

【 授权许可】

Unknown