Mitochondrial GTPase involved in mitochondrial trafficking (PubMed:16055062, PubMed:16717129, PubMed:22396657). Forms an essential protein complex with Milt that links Khc to mitochondria for light chain-independent, anterograde transport of mitochondria (PubMed:16717129). Required for axonal transport to synapses within nerve terminals (PubMed:16055062, PubMed:22396657). Required presynaptically but not postsynaptically at neuromuscular junctions (NMJs) (PubMed:16055062). Also involved in the regulation of mitochondrial dynamics by promoting drp1-mediated mitochondrial fission during high calcium conditions, and negatively regulating fission during normal conditions (PubMed:27716788). Interacts with kinesin-associated protein milt (PubMed:14605208, PubMed:16717129). Interacts with vimar (PubMed:27716788). Flies die at early pupal stage and exhibit abnormal locomotion (PubMed:16055062). Mitochondria in muscles and neurons are abnormally distributed (PubMed:16055062). Instead of being transported into axons and dendrites, mitochondria accumulate in parallel rows in neuronal somata (PubMed:16055062). Mutant NMJs lack presynaptic mitochondria, but neurotransmitter release and acute Ca(2+) buffering is only impaired during prolonged stimulation (PubMed:16055062). RNAi-mediated knockdown perturbs mitochondrial distribution and dynamics (PubMed:27716788). RNAi-mediated knockdown in the dopaminergic (DA) neurons decreases mitochondrial length and mitochondrial flux, and mitochondria accumulate in the most distal boutons of the DA motor neuron nerve terminals (PubMed:22396657). Belongs to the mitochondrial Rho GTPase family.