Identification of a Drosophila gene encoding a calmodulin-binding protein with homology to the trp phototransduction gene

We have isolated a number of Drosophila cDNAs on the basis of their encoding calmodulin-binding proteins. A full-length cDNA clone corresponding to one of these genes has been cloned and sequenced. Conservation of amino acid sequence and tissue-specific expression are observed between this gene and the transient receptor potential ( trp) gene. We propose the name transient receptor potential-like ( trpl) to describe this newly isolated gene. The trpl protein contains two possible calmodulin-binding sites, six transmembrane regions, and a sequence homologous to an ankyrin-like repeat. Structurally, the trpl and trp proteins resemble cation channel proteins, particularly the brain isoform of the voltage-sensitive Ca 2+ channel. The identification of a protein similar to the trp gene product, yet also able to bind Ca 2+/calmodulin, allows for a reinterpretation of the phenotype of the trp mutation and suggests that both genes may encode light-sensitive ion channels.