Highly selective and weak inward-rectifying potassium channel. Plays a role in both loading and unloading potassium into/from the phloem sap. Seems to control sugar loading into phloem via a voltage-dependent process. Blocked by physiological concentrations of external calcium and by external acidification. May interact with the cytoskeleton or with regulatory proteins. Dephosphorylation by PP2CA not only leads to the inhibition of potassium currents but also to an increase of the voltage-dependence of the channel. Regulated by the CBL4/CIPK6 calcium sensor/protein kinase complex via a kinase interaction-dependent but phosphorylation-independent translocation of the channel to the plasma membrane. The potassium channel is probably composed of a homo- or heterotetrameric complex of pore-forming subunits. Interacts with the phosphatase PPC2A and the kinase CIPK6. May interact with AKT1, KAT1 and KAT3. Interacts with SLAC1 (PubMed:27002025). Targeted to the cell membrane when interacting with CIPK6 and CBL4. Expressed mainly in the phloem tissues throughout the plant but also, at a lower level, in leaf epiderm, mesophyll and guard cells. In shoots, strongly induced by abscisic acid (ABA) treatment and reduced after NaCl treatment or potassium starvation. The segment S4 is probably the voltage-sensor and is characterized by a series of positively charged amino acids. The pore-forming region H5 is enclosed by the transmembrane segments S5 and S6 in the Shaker-type (1P/6TM) and contains the GYGD signature motif which seems to be involved in potassium selectivity. The KHA domain (rich in hydrophobic and acidic residues) present in the C-terminal part is likely to be important for tetramerization. Dephosphorylated by PP2CA. Delayed development and flowering. Belongs to the potassium channel family. Plant (TC 1.A.1.4) subfamily. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus.