May act as a transcriptional coregulator during muscle development through its interaction with SNW1. Has lost its ancestral function as a Na,K-ATPase beta-subunit (By similarity). Does not associate with known Na,K-ATPase alpha-subunits (By similarity). Associates with a SMAD7-transcriptional complex. Interacts with SNW1 and TOR1AIP1. Detected in nuclear envelops. Expressed in perinatal myocytes (at protein level). Expressed during postnatal development in skeletal muscle and heart. Belongs to the X(+)/potassium ATPases subunit beta family.