FIGURE 2.

Structural requirements for Ptch1 oligomerization. A, schematic illustrating additional mutants of Ptch1 containing discrete deletions in the middle loop and C-terminal domains. Numbers indicate boundaries of deleted amino acids. B, Ptch1 deletion mutants were co-transfected with ^HAC-term. Immunoprecipitation (IP) of Ptch1 shows binding of the isolated C-terminal domain of Ptch1 to the full-length, ΔML, and ΔC mutants but not to mutants with deletions simultaneously in the middle loop and C terminus. IB, immunoblot. C, co-expression and immunoprecipitation of the Ptch1 mutants with a GFP-tagged middle loop construct shows that the middle loop domain also binds to Ptch1 mutants with deletions in either the middle loop or C terminus but not when both deletions are present simultaneously. All blots are representative of at least two independent experiments. SSD, sterol sensing domain.