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Publication Abstract from PubMed

Two-pore channels (TPCs) contain two copies of a Shaker-like six-transmembrane (6-TM) domain in each subunit and are ubiquitously expressed in both animals and plants as organellar cation channels. Here we present the crystal structure of a vacuolar two-pore channel from Arabidopsis thaliana, AtTPC1, which functions as a homodimer. AtTPC1 activation requires both voltage and cytosolic Ca2+. Ca2+ binding to the cytosolic EF-hand domain triggers conformational changes coupled to the pair of pore-lining inner helices from the first 6-TM domains, whereas membrane potential only activates the second voltage-sensing domain, the conformational changes of which are coupled to the pair of inner helices from the second 6-TM domains. Luminal Ca2+ or Ba2+ can modulate voltage activation by stabilizing the second voltage-sensing domain in the resting state and shift voltage activation towards more positive potentials. Our Ba2+-bound AtTPC1 structure reveals a voltage sensor in the resting state, providing hitherto unseen structural insight into the general voltage-gating mechanism among voltage-gated channels.

Structure of the voltage-gated two-pore channel TPC1 from Arabidopsis thaliana.,Guo J, Zeng W, Chen Q, Lee C, Chen L, Yang Y, Cang C, Ren D, Jiang Y Nature. 2015 Dec 21. doi: 10.1038/nature16446. PMID:26689363^[3]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.