Highly selective inward-rectifying potassium channel that mediates potassium uptake by plant roots. Assuming opened or closed conformations in response to the voltage difference across the membrane, the channel is activated by hyperpolarization. May be a major salt-sensitive potassium channel in roots. The potassium channel is probably a homo- or heterotetrameric complex of pore-forming subunits. Expressed in roots and coleoptile of young seedlings. Down-regulated by salt stress. 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 (By similarity). The KHA domain (rich in hydrophobic and acidic residues) present in the C-terminal part is likely to be important for tetramerization. Belongs to the potassium channel family. Plant (TC 1.A.1.4) subfamily.