In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 108, No. 48 ( 2011-11-29), p. 19234-19239
Abstract:
Specialized proteins in the plasma membrane, endoplasmic reticulum (ER), and mitochondria tightly regulate intracellular calcium. A unique mechanism called store-operated calcium entry is activated when ER calcium is depleted, serving to restore intra-ER calcium levels. An ER calcium sensor, stromal interaction molecule 1 (STIM1), translocates within the ER membrane upon store depletion to the juxtaplasma membrane domain, where it interacts with intracellular domains of a highly calcium-selective plasma membrane ion channel, Orai1. STIM1 gates Orai1, allowing calcium to enter the cytoplasm, where it repletes the ER store via calcium-ATPases pumps. Here, we performed affinity purification of Orai1 from Jurkat cells to identify partner of STIM1 (POST), a 10-transmembrane–spanning segment protein of unknown function. The protein is located in the plasma membrane and ER. POST-Orai1 binding is store depletion-independent. On store depletion, the protein binds STIM1 and moves within the ER to localize near the cell membrane. This protein, TMEM20 (POST), does not affect store-operated calcium entry but does reduce plasma membrane Ca 2+ pump activity. Store depletion promotes STIM1–POST complex binding to smooth ER and plasma membrane Ca 2+ ATPases (SERCAs and PMCAs, respectively), Na/K-ATPase, as well as to the nuclear transporters, importins-β and exportins.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.1117231108
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
2011
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
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