1.A.1.4.6
Heterotetrameric K⁺ channel, KAT2/AKT2/KCT2 (Nieves-Cordones et al. 2014). Forms heteromeric channels (2:2 stoichiometry) with KAT1 (1.A.1.4.7) (Lebaudy et al., 2010) (Properties differ from those of homomeric channels; Xicluna et al., 2007).  KAT2 also forms homomeric channels in the plasma membrane (Nieves-Cordones et al. 2014). AKT2 functions in phloem loading and unloading and operates as an inward-rectifying channel that allows H⁺-ATPase-energized K⁺ uptake. Through reversible post-translational modifications, it can also function as an open, K⁺-selective channel, providing energy for transmembrane transport processes. It is present in a complex of several proteins in which it interacts with the receptor-like kinase, MRH1/MDIS2 (Sklodowski et al. 2017). The ortholog in Brassica rapa (Chinese cabbage), KCT2, is induced by stress. It has a TxxTxGYGD motif in the P-domain and a putative cyclic nucleotide-binding-like domain within a long C-terminal region (Zhang et al. 2006). HAK/KUP/KT8, GrAKT2.1 and GrAKT1.1 potassium channels may function in response to abiotic stress in Gossypium raimondii (Azeem et al. 2021).