Regulatory subunit of TRPV1, a molecular sensor of noxious heat and capsaicin. Positively regulates TRPV1 channel activity via phosphatidylinositol 4,5-bisphosphate (PIP2). Binds various phosphoinositide, including phosphatidylinositol 4,5-bisphosphate (PIP2), but not phosphatidylinositol (PI) (By similarity). . This is the function of ENSG00000233670 (PIRT, phosphoinositide interacting regulator of transient receptor potential channels).