Molecular mechanism of store-operated ca2+ signaling and crac channel activation mediated by stim & orai
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Store-operated Ca2+ (SOC) channels in the plasma membrane (PM) open when Ca2+ is depleted within the lumen of the endoplasmic reticulum (ER). SOC channels can be highly selective Ca2+ channels that are, under physiological conditions, impermeable to monovalent cations such as sodium or potassium; or Ca2+-permeable but relatively non-selective cation channels. The former are known as Ca2+-release-activated Ca2+ (CRAC) channels, which mediate sustained Ca2+ signaling in T cells in response to antigen presentation. This chapter summarizes biophysical properties of the CRAC channel in relation to the molecular physiology of STIM and Orai coupling. It begins by describing the biophysical properties of the CRAC channel. Ion channel functional properties are generally characterized in terms of gating (modes of opening and closing), ion selectivity, single-channel conductance, modulation, and pharmacology. Under this, it considers STIM as the ER Ca2+ sensor and STIM as the messenger to the plasma membrane. Furthermore, it discusses how Orai forms the Ca2+-selective pore of the CRAC channel. Finally, it takes up the phenomenon of STIM-induced activation of Orai channels. © 2010 Elsevier Inc. All rights reserved.
author list (cited authors)
Penna, A., Zhang, S. L., Yeromin, A. V., & Cahalan, M. D.
Handbook of Cell Signaling, 2/e