Thapsigargin discriminates strongly between Ca2+‐ATPase phosphorylated intermediates with different subcellular distributions in bovine adrenal chromaffin cells

FEBS Letters

Treiman, Marek¹  Caspersen, Casper¹ 

[1] Department of Medical Physiology, Biotechnology Center for Signal Peptide Research, University of Copenhagen, Copenhagen, Denmark

关键词: Ca2+-ATPase;    Thapsigargin;    Chromaffin cell;    Endoplasmic reticulum;    Ca2+ store;    DMSO;    dimethyl sulfoxide;    E∼P;    phosphorylated intermediate;    ER;    endoplasmic reticulum;    kDa;    kilodaltons;    PAGE;    polyacrylamide gel electrophoresis;    RSA;    relative specific activity;    SERCA;    sarco(endo)plasmic reticulum calcium ATPase;    SDS;    sodium dodecyl sulphate;    TES;    N-tris(hydroxymethyl)methyl-2-amino-methanesulfonic acid;   

DOI  :  10.1016/0014-5793(95)01304-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

We studied the effects of thapsigargin on the formation of the phosphorylated intermediates (E∼Ps) of endoplasmic reticulum Ca²⁺-ATPases in microsomes from bovine adrenal medulla. When submicrosomal fractions were separated on a sucrose gradient, two components of 100 kDa Ca²⁺-ATPase E∼P displaying distinct subcellular distributions were resolved. The first component was defined by Ca²⁺-induced protection against thapsigargin inhibition. The second component did not display such protection, with a 3 orders of magnitude difference in thapsigargin inhibitory potency towards the 2 components. In the absence of Ca²⁺, both E∼P components were highly sensitive to thapsigargin inhibition, revealing the presence of high-affinity thapsigargin-binding sites characteristic of SERCA ATPases. These data demonstrate a new level of molecular heterogeneity among Ca²⁺-ATPases of endoplasmic reticulum, and provide the first evidence of differential subcellular localization of individual Ca²⁺ pump subtypes in cells of neural origin.

【 授权许可】

Unknown