Transmembrane Ca2+ gradient is essential for high anion transport activity of human erythrocytes

被引:2
|
作者
Tu, YP
Feng, C
Xu, H
Guang, ZY
Lu, QW
Yang, FY
机构
[1] ACAD SINICA,NATL LAB BIOMACROMOL,BEIJING 100101,PEOPLES R CHINA
[2] ACAD SINICA,INST BIOPHYS,CTR EXPT TECHNOL,BEIJING 100101,PEOPLES R CHINA
关键词
transmembrane Ca2+ gradient; anion transport activity; Band; 3; freeze-fracture; resealed erythrocyte ghosts;
D O I
10.1007/BF01855014
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The role of a transmembrane Ca2+ gradient in anion transport by Band 3 of human resealed erythrocyte ghosts has been studied. The results show that a transmembrane Ca2+ gradient is essential for the conformation of erythrocyte Band 3 with higher anion transport activity. The dissipation of the transmembrane Ca2+ gradient by the ionophore A23187 inhibits the anion transport activity. The extent of this inhibition approaches 90% as the Ca2+ concentration on both sides of the ghost membrane is increased to 1.0 mM and half-maximum inhibition is observed at 0.25 mM Ca2+. Addition of ATP (0.4 mM) to the resealing medium can partly reestablish the transmembrane Ca2+ gradient by activation of Ca2+-ATPase and alleviate the inhibition to some extent. N-ethylmaleimide, an inhibitor of erythrocyte Ca2+-ATPase, prevents such restoration. Electron micrographs reveal that numerous larger intramembranous particles can be observed on the P-faces of freeze-fractured resealed ghosts in the absence of a transmembrane Ca2+ gradient.
引用
收藏
页码:299 / 311
页数:13
相关论文
共 50 条