Figure 4.
Models of compositional control for the ciliary membrane
A, The transition zone contains binding sites for select ciliary membrane proteins [52], and live imaging studies have shown that SMO pauses in the transition zone [78]. Thus, the transition zone may control the entry and exit of membrane-associated proteins from the cilium. B, The BBSome exports and imports ciliary membrane proteins such as GPCRs. C, A membrane diffusion barrier retains ciliary membrane proteins and excludes non-ciliary membrane proteins. D, Intraflagellar transport complexes enrich or deplete proteins in the cilium by coordinating with BBSome-facilitated trafficking across the transition zone.