TPC1 / TPC2 | Two Pore Segment Channel 1 and 2
Two Pore Segment Channels
2 members: TPC1, TPC2
The channel protein contains two repeats (domains I and II). Each of the two repeats contains five hydrophobic transmembrane segments (S1, S2, S3, S5, S6) and one positively charged transmembrane segment (S4). TPCs are formed by two transmembrane non-equivalent tandem Shaker-like pore-forming subunits, dimerized to form quasi-tetramers.
Regulation and function:
Activation of TPCs is induced by a decrease in transmembrane potential, or by an increase in calcium concentrations in the cytosol. Low pH of the lumen and low calcium concentration could cause inhibition of these channels. Expression of TPCs are found in both plant vacuoles and animal acidic organelles (endosomes and lysosomes). TPCs regulate sodium and calcium ion conductance, intravesicular pH, and trafficking excitability.