Illustration of the transient receptor potential subfamily V, member 1 (TRPV1) receptor. TRPV1 is a transmembrane protein that transports cations (positively charged ions) into a cell. It is activated by a number of physical and chemical stimuli including temperatures over 43 degrees Celsius, capsaicin (the molecule that gives chilies their heat) and acidic conditions. Its activation leads to a painful burning sensation. It is found mainly in the nociceptive (pain-sensing) neurons of the peripheral nervous system and is involved in body temperature regulation.