Please use this identifier to cite or link to this item: https://hdl.handle.net/2440/51979
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Type: Journal article
Title: Properties of Orai1 mediated store-operated current depend on the expression levels of STIM1 and Orai1 proteins
Author: Scrimgeour, N.
Litjens, T.
Ma, L.
Barritt, G.
Rychkov, G.
Citation: The Journal of Physiology, 2009; 587(12):2903-2918
Publisher: Blackwell Publishing Ltd
Issue Date: 2009
ISSN: 0022-3751
1469-7793
Statement of
Responsibility: 
N. Scrimgeour, T. Litjens, L. Ma, G. J. Barritt and G. Y. Rychkov
Abstract: Two cellular proteins, stromal interaction molecule 1 (STIM1) and Orai1, are recently discovered essential components of the Ca2+ release activated Ca2+ (CRAC) channel. Orai1 polypeptides form the pore of the CRAC channel, while STIM1 plays the role of the endoplasmic reticulum Ca2+ sensor required for activation of CRAC current (I(CRAC)) by store depletion. It is not known, however, if the role of STIM1 is limited exclusively to Ca2+ sensing, or whether interaction between Orai1 and STIM1, either direct or indirect, also defines the properties of I(CRAC). In this study we investigated how the relative expression levels of ectopic Orai1 and STIM1 affect the properties of I(CRAC). The results show that cells expressing low Orai1 : STIM1 ratios produce I(CRAC) with strong fast Ca2+-dependent inactivation, while cells expressing high Orai1 : STIM1 ratios produce I(CRAC) with strong activation at negative potentials. Moreover, the expression ratio of Orai1 and STIM1 affects Ca2+, Ba2+ and Sr2+ conductance, but has no effect on the current in the absence of divalent cations. The results suggest that several key properties of Ca2+ channels formed by Orai1 depend on its interaction with STIM1, and that the stoichiometry of this interaction may vary depending on the relative expression levels of these proteins.
Keywords: Cell Line
Humans
Boron Compounds
Barium
Calcium
Strontium
Calcium Channels
Membrane Proteins
Neoplasm Proteins
Calcium Channel Agonists
Blotting, Western
Patch-Clamp Techniques
Cloning, Molecular
Transfection
Electrophysiology
Calcium Signaling
Kinetics
Plasmids
Stromal Interaction Molecule 1
ORAI1 Protein
DOI: 10.1113/jphysiol.2009.170662
Grant ID: ARC
Appears in Collections:Aurora harvest
Molecular and Biomedical Science publications

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