Any of a large family of proteins that form various ion channels in the outer membrane of cells. They occur in both vertebrate and invertebrates and are involved in sensory perception for a wide range of stimuli, including temperature, pain, taste, and mechanical force. Binding of, say, a sour substance to TRP channels in a taste bud receptor cell will trigger transient opening of the channel, allowing the entry of calcium ions; this prompts release of neurotransmitter, which causes depolarization of adjacent sensory neurons, thereby sending a signal to taste centres in the brain.