RT Journal Article SR Electronic T1 Phenotypes of trpl Mutants and Interactions between the Transient Receptor Potential (TRP) and TRP-Like Channels inDrosophila JF The Journal of Neuroscience JO J. Neurosci. FD Society for Neuroscience SP 6797 OP 6803 DO 10.1523/JNEUROSCI.20-18-06797.2000 VO 20 IS 18 A1 Leung, Hung-Tat A1 Geng, Chaoxian A1 Pak, William L. YR 2000 UL http://www.jneurosci.org/content/20/18/6797.abstract AB The trp and trpl genes are thought to encode two classes of light-activated ion channels inDrosophila. A previous report indicated that a nulltrpl mutant does not display any mutant phenotype. This lack of detectable mutant phenotypes made it difficult to suggest functions for the transient receptor potential-like (TRPL) channel in photoreceptor responses. Here, the properties of trplphotoreceptor responses were studied by using electroretinogram (ERG) and intracellular recording techniques in combination with light stimuli of relatively long durations. Distinct mutant phenotypes were detectable under these conditions. These consisted of a reduced sustained component, oscillations superimposed on the response, a poststimulus hyperpolarization, and altered adaptation properties to dim background light. Comparison of photoreceptor responses obtained from wild type, trp, and trpl showed that the responses obtained from the trp andtrpl null mutants did not sum up to that of the wild-type response. To explain the nonlinear summation at the peak of the response, Reuss et al. (1997) proposed that Ca2+ions entering through the TRP channel modulate TRP and TRPL channel activities differentially. However, nonlinear summation was present not only at the peak but throughout the duration of response. Two lines of evidence are presented to suggest that, in addition to the interaction proposed by Reuss et al. (1997), there are other forms of interactions between TRP and TRPL channels, probably involving the channel proteins themselves.