Privileged coupling between Ca²⁺ entry through plasma membrane store-operated Ca²⁺ channels and the endoplasmic reticulum Ca²⁺ pump

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• 作者：Marí ; a Teresa Alonso ; Isabel M. Manjarré ; s ; Javier Garcí ; a-Sancho ; ^{jgsancho@ibgm.uva.es}
• 关键词：GFP ; green fluorescent protein ; YFP ; yellow fluorescent protein ; ER ; endoplasmic reticulum ; SERCA ; sarco/endoplasmic reticulum Ca2+ ATPase ; [Ca2+]C ; cytosolic free Ca2+ concentration ; [Ca2+]ER ; Ca2+ concentration inside ER ; [Ca2+]M ; Ca2+ concentration ins
• 刊名：Molecular and Cellular Endocrinology
• 出版年：2012
• 期刊代码：109_03037207
• 类别：bio
• 出版时间：28 April, 2012
• 卷：353
• 期：1-2
• 页码：37-44
• 文件大小：776 K

摘要

The sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) is the third element of capacitative calcium entry. It colocalizes with STIM1 and Orai1 at puncta, where couples plasma membrane store-operated Ca²⁺ channels (SOC) to Ca²⁺ pumping into the ER. The efficiency of this calcium entry-calcium refilling (CECR) coupling is comparable to the classic excitation-response transduction mechanisms. This allows efficient filling of the endoplasmic reticulum (ER) with the Ca²⁺ entering through SOC channels with little progression of the Ca²⁺ wave towards the cell core. CECR coupling is very sensitive to changes in stoichiometry among STIM, Orai and SERCA, with excess Orai antagonizing ER refilling. ER takes up most of the calcium load that enters through SOC, whereas mitochondria take up a very small fraction. This difference is due to the spatial positioning with regard to SOC, the amplitude of the high Ca²⁺ microdomains, and the differences in the Ca²⁺ affinity of the uptake mechanisms.