A region of the TRPV1 protein that functions as a temperature switch (FIG. 1) has been identified, and can be expressed, purified and applied in combination with other proteins. The function of the switch is maintained even when the region or domain is isolated from the entire protein. As the protein domain is a temperature switch, it can be used to control other proteins and signaling pathways in vitro and in vivo; and TRPV1 is a therapeutic target that is being pursued primarily for intervention in pain (neuropathic and inflammatory) and cancer.