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.

12 跨膜蛋白 Patched (Ptc1) 通过消耗细胞质膜小叶中激活下游调节因子所需的甾醇，充当 Hedgehog (Hh) 信号传导的抑制因子。正调节剂 Hh 通过与 Ptc1 及其共同受体结合来抑制 Ptc1 的转运蛋白功能，这些共同受体局部集中在称为小窝的内陷微区中。在这里，我们将小鼠 Ptc1 重组为脂质纳米圆盘，并使用单粒子低温电子显微镜确定其结构。该结构总体上类似于两性苯丙醇和去污剂中的结构，但在跨膜区域显示出各种构象差异。虽然大多数粒子显示单体，我们观察到 Ptc1 二聚体具有不同的相互作用模式和不同的膜曲率，其中一些让人联想到小窝。我们发现富含疏水性和芳香族残基的膜外“握手”区域在不同的膜曲率下介导了 Ptc1 间的相互作用。我们的数据为高度弯曲的陷窝中的 Ptc1 聚类提供了一个合理的框架。