Involved in endocytic trafficking by stabilizing organelles of the endocytic pathway. Probably acts as a cytoskeletal linker protein required to tether endosome vesicles to the cytoskeleton. Involved in modulation of endocytosis at stages required for down-regulation of membrane proteins that control synapse size. Not involved in synaptic vesicle recycling. Required in R7 cells for boss endocytosis into multivesicular bodies (MVBs). Has a role in regulating adult longevity. Homodimer. Interacts with microtubules via its N-terminus. Enriched at neuromuscular synapses, in both presynaptic and postsynaptic regions. The coiled coil domain mediates homodimerization. Belongs to the hook family.