Abstract
We cloned cDNA of putative outward-rectifying K+ channel gene from 2 varieties of rice, Hitomebore and Hidekomochi. Deduced amino acids contain 4 putative membrane-spanning domains and tandem two -TXGYGD-motifs of typical outward-rectifying K+ channels. One copy of the gene (ROK, rice outward-rectifying K+ channel) identified from the data base of Oryza sativa japonica L. cv. Nipponbare supported southern blotting analysis. The ROK showed 26, 23 % identical amino acids to inward-rectifying K+ channels of KAT1, AKT2, and 34, 39, 33, 40 % to outward-rectifying of KCO1, KCO2, KCO3, KCO5 from Arabidopsis thaliana, respectively. Phylogenetic tree of plant K+ channels supported the ROK in outward-rectifying groups. Expression analysis of the gene revealed 3-5 times higher level in anthers than in leaves, stems, roots of those rice plants by RT-PCR southern hybridization and real time PCR detection. Molecular size of the ROK expressed in yeast cells is about 50kD by gel-shift analysis.
