Proteoliposomes with right‐side‐out oriented purple membrane/bacteriorhodopsin require cations inside for proton pumping

FEBS Letters

Ihara, Kunio¹  Mukohata, Yasuo¹ 

[1] Department of Biology, Faculty of Science, Osaka University, Toyonaka 560, Japan

关键词: Bacteriorhodopsin;    Proton pumping;    Purple membrane;    Proteoliposome;   

DOI  :  10.1016/0014-5793(88)80357-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Proteoliposomes were prepared by sonication of phospholipids and blue membranes (cation-free purple membranes carrying little activity of light-driven proton pumping) in an acidic medium of very low ionic strength. The majority of the bacteriorhodopsin population in these proteoliposomes was in the right-side-out (as in living cells) orientation as judged from the resultant polypeptides after papain digestion. By raising the pH of sonication, the population of right-side-out oriented bacteriorhodopsin decreased, and consequently that of the inversely oriented one increased. In KCl and NaCl up to certain concentrations or in choline chloride even at high concentrations, in the light, the proteoliposomes with right-side-out bacteriorhodopsin did not pump protons, whereas those with inversely oriented bacteriorhodopsin did. The former began to pump only after cations were likely incorporated/permeated into the proteoliposome and reached the carboxyl terminal (cytosol) side of bacteriorhodopsin/purple membrane.

【 授权许可】

Unknown