Regulates mitochondrial aggregation and transport in axons in living neurons. May link mitochondria to the Trak2-kinesin motor complex via its interaction with Miro and Trak2. Mitochondrial distribution and dynamics is regulated through Armcx3 protein degradation, which is promoted by PCK and negatively regulated by Wnt1. Enhances the Sox10-mediated transactivation of the neuronal acetylcholine receptor subunit alpha-3 and beta-4 subunit gene promoters. Interacts (via ARM domain) with MIRO1, MIRO2 and TRAK2. The interaction with Miro is calcium-dependent. Interacts with Sox10. Belongs to the eutherian X-chromosome-specific Armcx family.