Tethering complexes in the endocytic pathway : CORVET and HOPS

Endocytosis describes the processes by which proteins, peptides and solutes but also pathogens enter the cell. Endocytosed material continues its way to endosomes. Genetic studies in yeast, worms, flies, and mammals have identified a set of universally conserved proteins that are essential for early-to-late endosome transition, lysosome biogenesis, and for endolysosomal trafficking pathways, including autophagy. The two Vps-C complexes, CORVET and HOPS, are among those factors performing diverse biochemical functions: they tether membranes, interact with Rab GTPases, activate and proofread SNARE assembly to drive membrane fusion, and possibly attach endosomes to the cytoskeleton. In addition, several of the CORVET and HOPS subunits have diversified in metazoans and probably give rise to additional specialized complexes to accomodate the higher complexity of trafficking pathways in these cells. Recent studies offer new insights into the complex relationships between CORVET and HOPS complexes and various other factors of the endolysosomal pathway. Interactions with the V-ATPase, the ESCRT machinery, phosphoinositides, the cytoskeleton and the Rab switch suggest an intricate cooperative network for endosome maturation. Accumulating evidence supports the view that endosomal tethering complexes implement a regulatory logic that governs endomembrane identity and dynamics. © 2013 The Authors Journal compilation © 2013 FEBS.