McDonough A A, Geering K, Farley R A
Department of Physiology and Biophysics, University of Southern California School of Medicine, Los Angeles 90033.
FASEB J. 1990 Apr 1;4(6):1598-605. doi: 10.1096/fasebj.4.6.2156741.
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 (alpha) and glycoprotein (beta) subunits. The beta 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 beta and summarize evidence that expression of both alpha and beta subunits is required for Na,K-ATPase activity, that inhibition of glycosylation causes a decrease in accumulation of both alpha and beta subunits, and we provide evidence that pretranslational up-regulation of beta alone can lead to increased abundance of sodium pumps. These findings are all consistent with the hypothesis that the beta subunit regulates, through assembly of alpha beta heterodimers, the number of sodium pumps transported to the plasma membrane.
钠泵Na,K-ATP酶位于所有动物细胞的质膜中，是离子转运ATP酶家族的成员之一，该家族成员共享高度同源的催化亚基。在这个家族中，只有Na,K-ATP酶被确定为催化（α）亚基和糖蛋白（β）亚基的异二聚体。β亚基与泵的转运或酶活性无关，直到最近，其在Na,K-ATP酶功能中的作用仍是个谜。在这篇综述中，我们描述了关于β亚基结构的已知信息，并总结了以下证据：Na,K-ATP酶活性需要α亚基和β亚基的共同表达；糖基化抑制会导致α亚基和β亚基的积累减少；我们还提供了证据表明，单独对β亚基进行翻译前上调可导致钠泵丰度增加。这些发现都与以下假设一致：β亚基通过αβ异二聚体的组装来调节转运到质膜的钠泵数量。
