Potassium Channel KAT3 (KAT3) Arabidopsis Thaliana Recombinant Protein

Encodes KAT3, a member of the Shaker family of voltage-gated potassium channel subunits. Does not form functional potassium channel on its own. Involved in down-regulating AKT1 and KAT1 channel activity by forming heteromers with AKT1 or KAT1. The Shaker family K+ ion channels include five groups based on phylogenetic analysis (FEBS Letters (2007) 581: 2357): I (inwardly rectifying conductance): AKT1 (AT2G26650), AKT5 (AT4G32500) and SPIK (also known as AKT6, AT2G25600); II (inward rectifying channel): KAT1 (AT5G46240) and KAT2 (AT4G18290); III (weakly inward rectifying channel): AKT2 (AT4G22200); IV (regulatory subunit involved in inwardly rectifying conductance formation): KAT3 (also known as AtKC1, AT4G32650); V (outward rectifying channel): SKOR (AT3G02850) and GORK (AT5G37500).

Function: Probable modulatory (alpha) subunit of inward-rectifying potassium channels. Could mediate potassium uptake from the soil solution by plant roots in association with AKT1. Ref.7 Ref.8

Subunit structure: The potassium channel is probably composed of a homo- or heterotetrameric complex of pore-forming subunits. May interact with AKT1 and AKT2.

Subcellular location: Membrane; Multi-pass membrane protein Ref.7.

Tissue specificity: Expressed predominantly in root hairs and root endodermis and, at a lower level, in leaf nodes, trichomes, and hydathodes. Ref.7 Ref.8

Induction: Strongly reduced in roots after 2,4-dichlorophenoxyacetic acid (2,4-D) treatment and after benzyladenine (BA) treatment. Strongly induced in shoots after NaCl treatment. Ref.8

Domain: 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.

Sequence similarities: Belongs to the potassium channel family. Plant (TC 1.A.1.4) subfamily. [View classification]Contains 1 cyclic nucleotide-binding domain.Contains 1 KHA domain.