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Formation of STIM and Orai complexes: puncta and distal caps
Author(s) -
Barr Valarie A.,
Bernot Kelsie M.,
Shaffer Meredith H.,
Burkhardt Janis K.,
Samelson Lawrence E.
Publication year - 2009
Publication title -
immunological reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.839
H-Index - 223
eISSN - 1600-065X
pISSN - 0105-2896
DOI - 10.1111/j.1600-065x.2009.00812.x
Subject(s) - orai1 , stim1 , immunological synapse , microbiology and biotechnology , endoplasmic reticulum , immune system , calcium , biology , calcium signaling , voltage dependent calcium channel , t cell , chemistry , immunology , t cell receptor , signal transduction , organic chemistry
Summary: In the last few years, great progress has been made in understanding how stromal interacting molecule 1 (STIM1), a protein containing a calcium sensor that is located in the endoplasmic reticulum, and Orai1, a protein that forms a calcium channel in the plasma membrane, interact and give rise to store‐operated calcium entry. Pharmacological depletion of calcium stores leads to the formation of clusters containing STIM and Orai that appear to be sites for calcium influx. Similar puncta are also produced in response to physiological stimuli in immune cells. In T cells engaged with antigen‐presenting cells, clusters containing STIM and Orai accumulate at the immunological synapse. We recently discovered that in activated T cells, STIM1 and Orai1 also accumulate in cap‐like structures opposite the immune synapse at the distal pole of the cell. Both caps and puncta are long‐lived stable structures containing STIM1 and Orai1 in close proximity. The function of puncta as sites of calcium influx is clear. We speculate that the caps may provide a secondary site of calcium entry. Alternatively, they may serve as a source of preformed channel complexes that move to new immune synapses as T cells repeatedly engage antigen‐presenting cells.