Abstract
Three types of K transport proteins, K channels, HKT, and KUP/KT/HAK have been identified in plants. The insertion process of voltage sensor of K channels involves a newly recognized second type of membrane protein integration process (Sato et al. PNAS 99, 60, 2002). HKT transporters contain eight transmembrane segments and four pore arranged in a mode similar to that of K channel tetramer (Kato et al. PNAS 98, 6488, 2001; Maser et al. PNAS 99, 6428, 2002). An Arabidopsis HKT1 functions as a selective Na transporter in Xenopus oocytes (Uozumi et al. Plant Physiol. 122, 1249, 2000). The athkt1 mutations suppressed the Na sensitive phenotype of the sos3 mutant (Rus et al. PNAS 98, 14150, 2001). The leaves in athkt1 disruption became hypersensitive to salt stress (Maser et al. FEBS Letters, 531, 157, 2002). These findings indicate that AtHKT1 functions as one of components involving Na transport pathway in Arabidopsis.
