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). Associates with a SMAD7-transcriptional complex. Interacts with TOR1AIP1. Does not associate with known Na,K-ATPase alpha-subunits (By similarity). Interacts with SNW1. Detected in nuclear envelops. Expressed in skeletal muscle (at protein level). Expressed during postnatal development in skeletal muscle and heart. Expressed in embryo 15.5 dpc, onward. Belongs to the X(+)/potassium ATPases subunit beta family.