S. purpuratus caveolin forms an 11-mer complex. (A–C) 3.1 Å resolution cryo-EM density map of the S. purpuratus caveolin complex with 11-fold symmetry. The complex is shown with ninety-degree rotated views displaying the cytoplasmic-facing surface (A), side (B), and membrane-facing surface (C). The complex has an overall disklike structure with 11 spiraling α-helices and a central β-barrel. A single protomer is highlighted in yellow. Scale bar, 20 Å. (D–F) Secondary structure model of the S. purpuratus caveolin in the same views as shown in panels A–C. (G and H) Secondary structure of S. purpuratus caveolin protomer with secondary features and N and C termini noted. (I) Central slice of the density map (purple) with the detergent micelle (gray). (J and K) AF2.2-predicted structure of the S. purpuratus caveolin 11-mer showing views of the cytoplasmic-facing surface (J) and side view (K). Structured regions predicted by AF2.2 that are not found in the cryo-EM structure are highlighted in burgundy. (L) Protomer from the AF2.2 11-mer model fit into the cryo-EM density map (gray outline) of a protomer.