This is the non-catalytic component of the active enzyme, which catalyzes the hydrolysis of ATP coupled with the exchange of Na(+) and K(+) ions across the plasma membrane. The beta subunit regulates, through assembly of alpha/beta heterodimers, the number of sodium pumps transported to the plasma membrane. Involved in cell adhesion and establishing epithelial cell polarity. The sodium/potassium-transporting ATPase is composed of a catalytic alpha subunit, an auxiliary non-catalytic beta subunit and an additional regulatory subunit. Interacts with catalytic subunit ATP12A (By similarity). Interacts with regulatory subunit FXYD1 (By similarity). Interacts with regulatory subunit FXYD3 (PubMed:15743908). Interacts with NKAIN1, NKAIN2 and NKAIN4 (PubMed:17606467). Interacts with MLC1 (By similarity). Part of a complex containing MLC1, TRPV4, AQP4 and HEPACAM (By similarity). Interacts with KIRREL3 (By similarity). Interacts with OBSCN (via protein kinase domain 1) (PubMed:23392350). Colocalizes with OBSCN at the intercalated disk and sarcolemma in cardiomyocytes. Localizes in long striations at the level of Z and M lines. Expressed in cardiac muscle and in flexor digitorum brevis (FDB) muscle (at protein level) (PubMed:23392350). Expressed in a circadian manner in the kidney and aorta (at protein level) (PubMed:30012868). The C-terminal lobe folds into an immunoglobulin-like domain and mediates cell adhesion properties. Glutathionylated (PubMed:21454534). N-glycosylated (By similarity). Belongs to the X(+)/potassium ATPases subunit beta family.