Probable voltage-independent potassium-selective tonoplast ion channel. Homodimer. Expressed in hydathodes and the vascular tissues of roots, stems, leaves and flowers. Each of the two pore-forming region (also called P-domain or P-loop) is enclosed by two transmembrane segments (2P/4TM) and contains the GYGD signature motif which seems to be involved in potassium selectivity. Belongs to the two pore domain potassium channel (TC 1.A.1.7) family.