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. Author manuscript; available in PMC: 2017 Jan 1.
Published in final edited form as: Trends Pharmacol Sci. 2015 Sep 29;37(1):62–72. doi: 10.1016/j.tips.2015.09.001

Figure 3. Models of Ptch-mediated Smo Regulation.

Figure 3

Several models for Ptch-mediated Smo regulation have been hypothesized. In A, Ptch (yellow) pumps an antagonist (black), which binds to cell-surface localized Smo to block its accumulation and signaling (magenta, inactive Smo). In B, Ptch pumps a Smo agonist (green) out of the cell (B) or sequesters it in vesicles (B′) where it is unable to bind and activate Smo. In C, Ptch controls activity of a lipid regulator to block accumulation of a specific lipid species in membrane microdomains that are permissive for Smo signaling (purple haze, active Smo shown in green).