Functional analysis of a rice putative voltage-dependent Ca2+ channel, OsTPC1, expressed in yeast cells lacking its homologous gene CCH1

We isolated a cDNA (OsTPC1) from rice that was homologous to AtTPC1, a putative voltage-dependent Ca2+ channel (VDCC) gene of Arabidopsis thaliana. The hydropathy profile of its deduced amino acid sequence showed significant structural features of the alphal-subunit of animal VDCCs. Functional analysis using a heterologous yeast expression system showed that OsTPC1 facilitates Ca2+ permeation. The K. value for Ca2+, of OsTPC1, 47.5 muM, was comparable to that of intrinsic CCH1, a candidate VDCC in yeast. Ca2+ permeation by OsTPC1 was inhibited by verapamil, a VDCC blocker. These findings indicate for the first time that OsTPC1 is a putative VDCC in rice.