Orai, STIM1 and iPLA2β: a view from a different perspective

VM Bolotina - 2008 - Wiley Online Library
VM Bolotina
2008Wiley Online Library
The mechanism of store‐operated Ca2+ entry (SOCE) remains one of the intriguing
mysteries in the field of Ca2+ signalling. Recent discoveries have resulted in the molecular
identification of STIM1 as a Ca2+ sensor in endoplasmic reticulum, Orai1 (CRACM1) as a
plasma membrane channel that is activated by the store‐operated pathway, and iPLA2β as
an essential component of signal transduction from the stores to the plasma membrane
channels. Numerous studies have confirmed that molecular knock‐down of any one of these …
The mechanism of store‐operated Ca2+ entry (SOCE) remains one of the intriguing mysteries in the field of Ca2+ signalling. Recent discoveries have resulted in the molecular identification of STIM1 as a Ca2+ sensor in endoplasmic reticulum, Orai1 (CRACM1) as a plasma membrane channel that is activated by the store‐operated pathway, and iPLA2β as an essential component of signal transduction from the stores to the plasma membrane channels. Numerous studies have confirmed that molecular knock‐down of any one of these three molecules impair SOCE in a wide variety of cell types, but their mutual relations are far from being understood. This report will focus on the functional roles of Orai1, STIM1 and iPLA2β, and will address some specific questions about Orai1 and TRPC1, and their relation to SOC channels in excitable and non‐excitable cells. Also, it will analyse the novel role of STIM1 as a trigger for CIF production, and the complex relationship between STIM1 and Orai1 expression, puncta formation and SOCE activation. It will highlight some of the most recent findings that may challenge simple conformational coupling models of SOCE, and will offer some new perspectives on the complex relationships between Orai1, STIM1 and iPLA2β in the SOCE pathway.
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