Guanine nucleotide exchange factor for Arf6 (PubMed:28607459). Regulates axon growth and branching by inhibiting microtubule polymerisation at the cortex (PubMed:31718774). Together with shot, promotes axonal microtubule bundle integrity (PubMed:31718774). Required for normal ethanol-induced tolerance and preference (PubMed:28607459). Probably by activating Arf6, counteracts ethanol-induced sedation (PubMed:28607459). Interacts (via MTED motif) with tubulin. Expressed in the head (at protein level). Expressed throughout the central nervous system at larval and adult stages. Viable but male sterile (PubMed:28607459). Results in enhances preference and sensitivity to ethanol (PubMed:28607459). Fails to develop tolerance to repeated ethanol exposures (PubMed:28607459). Increases axon length and axon branching (PubMed:31718774). RNAi-mediated knockdown increases axon length and axon branching (PubMed:31718774). RNAi-mediated knockdown in a subset of lamina neurons results in axonal swellings and disorganized axonal microtubules (PubMed:31718774). Belongs to the PSD family.