The human homologue of the Drosophila gene patched. PTCH1 encodes a transmembrane protein with homology to bacterial proton-driven transmembrane molecular transporters and represses genes encoding members of the transforming growth factor β and Wnt families of signalling proteins. Smoothened and patched mediate the cellular response to the hedgehog secreted protein signal. A second gene, PTCH2, has high homology. See Gorlin's syndrome.