Formation of the B9-domain protein complex MKS1–B9D2–B9D1 is essential as a diffusion barrier for ciliary membrane proteins

Abstract

Meckel syndrome (MKS)1, B9 domain (B9D)1, and B9D2 are soluble transition zone (TZ) proteins and share a B9D. We demonstrate the interaction mode of these B9D proteins to be MKS1-B9D2-B9D1 and their interdependent localization to the TZ. We also show that formation of the B9D protein complex is crucial for creating a diffusion barrier for ciliary membrane proteins.