The 12-transmembrane protein Patched (Ptc1) acts as a suppressor for Hedgehog (Hh) signaling by depleting sterols in the cytoplasmic membrane leaflet that are required for the activation of downstream regulators. The positive modulator Hh inhibits Ptc1's transporter function by binding to Ptc1 and its co-receptors, which are locally concentrated in invaginated microdomains known as caveolae. Here, we reconstitute the mouse Ptc1 into lipid nanodiscs and determine its structure using single-particle cryoelectron microscopy. The structure is overall similar to those in amphipol and detergents but displays various conformational differences in the transmembrane region. Although most particles show monomers, we observe Ptc1 dimers with distinct interaction patterns and different membrane curvatures, some of which are reminiscent of caveolae. We find that an extramembranous "hand-shake" region rich in hydrophobic and aromatic residues mediates inter-Ptc1 interactions under different membrane curvatures. Our data provide a plausible framework for Ptc1 clustering in the highly curved caveolae. [Display omitted] • The Hedgehog receptor Ptc1 from mouse was reconstituted into lipid nanodisc • Structure of Ptc1 in lipid membrane is overall similar to that in amphipol/detergents • An N-terminal helix is important but not essential for Ptc1 activity • Different homodimers are observed along with different membrane curvatures The Hedgehog receptor Ptc1 is localized in curved membrane microdomains called caveolae. Using cryo-EM, Luo et al. determined the monomeric structure of Ptc1 in lipid nanodiscs. They also observed various dimers associated with caveolae-like membrane curvatures. The findings suggest how Ptc1 clusters in curved membranes for its signaling function. [ABSTRACT FROM AUTHOR]