Two-pore channels (TPCs) are eukaryoticintracellularvoltage-gated and ligand gated cation selective ion channels.[1] There are two known paralogs in the human genome, TPC1s and TPC2s.[2] In humans, TPC1s are sodium selective and TPC2s conduct sodium ions, calcium ions and possibly hydrogen ions. Plant TPC1s are non-selective channels. Expression of TPCs are found in both plant vacuoles and animal acidic organelles.[3] These organelles consist of endosomes and lysosomes.[3] TPCs are formed from two transmembrane non-equivalent tandem Shaker-like, pore-forming subunits, dimerized to form quasi-tetramers. Quasi-tetramers appear very similar to tetramers, but are not quite the same.[1][3] Some key roles of TPCs include calcium dependent responses in muscle contraction(s), hormone secretion, fertilization, and differentiation.[citation needed] Disorders linked to TPCs include membrane trafficking, Parkinson's disease, Ebola, and fatty liver.[4][5][6][7]
As implied by their name, TPC channels possess two pores and were named for their two Shaker-like repeats, which each have a pore domain.[1][8][9][10][11] This contrasts with two-pore-domain potassium channels, which confusingly have only one pore and were named for the fact that each subunit has two P (pore) domains in its primary sequence.[12][13]
^Yu FH, Catterall WA (October 2004). "The VGL-chanome: a protein superfamily specialized for electrical signaling and ionic homeostasis". Science's STKE. 2004 (253): re15. doi:10.1126/stke.2532004re15. PMID15467096. S2CID19506706.
