Potassium channel involved in coordination of muscle contraction (PubMed:14534247). Activity is regulated by sup-18 (PubMed:24586202). May form a complex with the regulatory subunits unc-93 and sup-10. Associated with dense bodies. Low levels along surface of body-wall muscle cells, in vulval and intestinal muscles and, more weakly, in anal depressor and sphincter muscles. Also expressed in a subset of head neurons. Expressed in body wall muscles from 3.5-fold stage of embryogenesis with highest levels in late embryos and L1 stage larvae. Lower levels persist to adulthood. Uncoordinated rubber band response is phenocopied by exposure to the unc-49 agonist muscimol. Belongs to the two pore domain potassium channel (TC 1.A.1.8) family.