Physiological significance of oligomeric associations of ionic pumps in biomembranes.

Some kinetic features of transport ATPases (Na, K-dependent and Ca-dependent) are characterized. The experimental data point to the existence of cooperative interactions between functional units of transport ATPases in membrane matrix. Detergent treatment showed that cooperativity with respect to the substrate is realized via interactions between several functional units (protomers), whereas cooperativity with respect to activating ions is manifested at the ion-binding sites of each protomer of transport ATPases. Structural changes in the ATPase molecules which reflect interprotein interactions induced by high ATP concentration have been revealed.