The sodium pump needs its 1 subunit

The sodium pump Na,K-ATPase, located in the plasma membrane of all animal cells, is a member of a family of ion-translocating ATPases that share highly homologous catalytic subunits. In this family, only Na,K-ATPase has been established to be a heterodimer of catalytic (a) and glycoprotein (/3) subunits. The /3 subunit has not been associated with the pump’s transport or enzymatic activity, and its role in Na,K-ATPase function has been, until recently, a puzzle. In this review we describe what is known about the structure of j3 and summarize evidence that expression of both a and j3 subunits is required for Na,K-ATPase activity, that inhibition of glycosylation causes a decrease in accumulation of both a and /3 subunits, and we provide evidence that pretranslational up-regulation of j3 alone can lead to increased abundance of sodium pumps. These findings are all consistent with the hypothesis that the /3 subunit regulates, through assembly of a(3 heterodirners, the number of sodium pumps transported to the plasma membrane.-McDoNouGH, A. A.; GEERING, K.; FARLEY, R. A. The sodium pump needs its /3 subunit. FASEBJ. 4: 1598-1605; 1990.