PTCH (Patched protein homolog 1) is a receptor for sonic hedgehog (SHH), indian hedgehog (IHH) and desert hedgehog (DHH). PTCH associates with the smoothened protein (SMO) to transduce the hedgehog's proteins signal.PTCH has a tumor suppressor function, as inactivation of this protein is probably a necessary, if not sufficient step for tumorigenesis. PTCH is expressed in the adult brain, lung, liver, heart, placenta, skeletal muscle, pancreas and kidney. It is also expressed in tumor cells but not in normal skin. During development PTCH is found in all major target tissues of sonic hedgehog, such as the ventral neural tube, somites, and tissues surrounding the zone of polarizing activity of the limb bud.
Defects in PTCH are probably the cause of basal cell nevus syndrome also known as Gorlin syndrome or Gorlin-Goltz syndrome.