May contribute to coordination of muscle contraction as regulatory subunit of a nonessential potassium channel complex (PubMed:1313436, PubMed:14534247). Plays a role in the formation of muscle connections, also called muscle arm extensions, between the body wall and the motor axons in the dorsal and ventral cord (PubMed:27123983). May form a complex with sup-9 and sup-10 where unc-93 and sup-10 act as regulatory subunits of the two pore potassium channel sup-9. Associated with dense bodies. Low levels in body-wall muscles, eight vulval muscles, intestinal muscles and a subset of head neurons. More highly expressed in L1 larvae than in eggs and adults. Defective extension of body wall muscle connections or arms towards the ventral nerve cord. Double knockout with madd-3 results in severe muscle arm extension defects. Gain of function phenotype is phenocopied by exposure to the unc-49 agonist muscimol. Belongs to the unc-93 family.