Required for the maintenance of appropriate synaptic retrograde communication and the stabilization of muscle cell architecture or physiology. May play a role in anchoring the cytoskeleton to the plasma membrane. Component of the dystrophin associated protein complex (DAPC). Interacts with Dg, via the Dg WW domain binding sites. Expressed in neuronally derived tissues, mainly the CNS and the brain of stage 16 embryos. Lower level expression is seen in the sensory organs. Expression is absent from the musculature. In larvae, expression is predominant throughout the neuropil and brain and in the eye antennal disks. Expressed both maternally and zygotically throughout development. Flies that have reduced expression of all isoforms (transgenic RNA interference targeting the common C-terminal region) exhibit severe muscle degeneration in larvae and adult flies. Muscles were either ruptured, absent or the fibers were detached from their attachment sites at tendon cells. These are necrotic, not apoptotic processes.