RAB-27 and its effector RBF-1 regulate the tethering and docking steps of DCV exocytosis in C. elegans.

The molecular mechanisms by which dense core vesicles (DCVs) translocate, tether, dock and prime are poorly understood. In this study, Caenorhabditis elegans was used as a model organism to study the function of Rab proteins and their effectors in DCV exocytosis. RAB-27/AEX-6, but not RAB-3, was found to be required for peptide release from neurons. By analyzing the movement of DCVs approaching the plasma membrane using total internal reflection fluorescence microscopy, we demonstrated that RAB-27/AEX-6 is involved in the tethering of DCVs and that its effector rabphilin/RBF-1 is required for the initial tethering and subsequent stabilization by docking.