The Drosophila transient receptor potential (trp) gene and its homologue, trpl, have been suggested to mediate calcium entry during the insect's phototransduction process. We isolated a human cDNA, human trp-1 (Htrp-1), encoding a polypeptide of 793 amino acids that is 37% identical (62% similar) to Drosophila trp and trpl. Northern analysis showed that the Htrp-1 transcript is approximately 5.5 kb and expressed in most human tissues, with higher amounts in ovary, testis, heart, and brain. Isolation of Htrp-1 suggests that a trp-type protein is present in mammals and should provide a useful tool in studying calcium-depletion induced calcium influx processes.
