Concepts of the oligomeric structure and function of Na, K-ATPase based on the results of studying ligand binding and of determining the size of the molecular target

This review is devoted to the discussion of the sizes and molecular structure of the minimal functional unit of Na, K-ATPase. Special attention is paid to the data obtained by radiation inactivation method and studies on ligand binding. The model for the stepwise radiation inactivation of Na, K-ATPase is proposed. The conclusion is drawn that Na, K-ATPase has a dimeric structure, the interactions between its alpha-subunits stabilize the quaternary structure of the pump. Functionally, each alpha-subunit in a stabilized structure possesses a full hydrolytic activity.