Patched 2 (Ptch2) is a 180 - 200 kDa 12 transmembrane member of the Patched family. Human PTCH2 is 1203 amino acids (aa) in length. It has two terminal cytoplasmic domains, one between aa 1 - 57, and a second between aa 1115 - 1203. Together with Smoothened (SMO), Ptch2 forms a membrane complex that serves as a receptor for Sonic Hedgehog (SHH).
Human Ptch2 likely has two isoforms. One shows an eight aa extension of the C-terminus, while a second shows a four aa substitution for the C-terminal 61 amino acids (aa 1143 - 1203). Over the first extracellular loop human Patched 2 shares 95% and 96% aa sequence identity with mouse and canine Patched 2, respectively.