Patched homolog 1 (PTC1) is a 170 - 175 kDa member of the Patched family of proteins. It is found on multiple cells types and forms a constitutive, inactivating complex with Smoothened. Upon SHH binding to PTC1, Smoothened is released and initiates downstream signaling.
Mouse PTC1 is a 12 transmembrane, 1434 aa glycoprotein that contains two terminal cytoplasmic domains. Only one mRNA species for PTC1 has been reported in mice. However, two or more splice forms exist, with variation occurring over the first 150 aa of the N-terminus. Over aa 108 - 422, mouse PTC1 shares 97% and 99% aa sequence identity with human and rat PTC1, respectively.