Dynamic movement of the calcium sensor STIM1 and the calcium channel orai1 in activated T-cells: Puncta and distal caps

Valarie A. Barr, Kelsie M. Bernot, Sonal Srikanth, Yousang Gwack, Lakshmi Balagopalan, Carole K. Regan, Daniel J. Helman, Connie L. Sommers, Masatsugu Oh-hora, Anjana Rao, Lawrence E. Samelson

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    Abstract

    The proteins STIM1 and Orai1 are the long sought components of the store-operated channels required in T-cell activation. However, little is known about the interaction of these proteins in T-cells after engagement of the T-cell receptor. We found that T-cell receptor engagement caused STIM1 and Orai1 to colocalize in puncta near the site of stimulation and accumulate in a dense structure on the opposite side of the T-cell. FRET measurements showed a close interaction between STIM1 and Orai1 both in the puncta and in the dense cap-like structure. The formation of cap-like structures did not entail rearrangement of the entire endoplasmic reticulum. Cap formation depended on TCR engagement and tyrosine phosphorylation, but not on channel activity or Ca2+ influx. These caps were very dynamic in T-cells activated by contact with superantigen pulsed B-cells and could move from the distal pole to an existing or a newly forming immunological synapse. One function of this cap may be to provide preassembled Ca2+ channel components to existing and newly forming immunological synapses.

    Original languageEnglish
    Pages (from-to)2802-2817
    Number of pages16
    JournalMolecular biology of the cell
    Volume19
    Issue number7
    DOIs
    Publication statusPublished - Jul 1 2008

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    All Science Journal Classification (ASJC) codes

    • Molecular Biology
    • Cell Biology

    Cite this

    Barr, V. A., Bernot, K. M., Srikanth, S., Gwack, Y., Balagopalan, L., Regan, C. K., ... Samelson, L. E. (2008). Dynamic movement of the calcium sensor STIM1 and the calcium channel orai1 in activated T-cells: Puncta and distal caps. Molecular biology of the cell, 19(7), 2802-2817. https://doi.org/10.1091/mbc.E08-02-0146