Somatosensory signaling is the process by which we become aware of external sensations such as touch, temperature or pain. Despite the importance of these sensory modalities to our everyday existence, we know relatively little about their molecular mechanisms. These sensations would appear to be quite different, however, recent work has shown that they may be separated by only a fine line at the molecular level. Two large ion channel families, the TRP channels and the ENaCs, appear to have been evolutionarily selected for a variety of physiological functions ranging from thermosensation and osmosensation to pain and touch. We have developed a genetic model system in Drosophila to examine the molecular components of somatosensory signal transduction in type II multiple dendritic(md) sensory neurons. We are applying a variety of techniques including electrophysiology, behavior, molecular biology and genetics to identify and characterize evolutionarily conserved signaling components.