Interaction of Na,K-ATPase catalytic subunit with cellular proteins and other endogenous regulators.

Some mechanisms of regulation of Na,K-ATPase activity in various tissues including the phosphorylation of the catalytic subunit of the enzyme by different protein kinases (PKA, PKC, and tyrosine kinase) and the interaction of the alpha-subunit with different proteins (Na,K-ATPase beta- and gamma-subunits, ankyrin, phosphoinositide-3 kinase, and AP-2 protein) and endogenous digitalis-like factors are considered. Special attention is given to the search for possible protein-partners including melittin-like protein and to the mechanism of enzyme regulation connected with the change of Na,K-ATPase quaternary structure. A recently discovered role of Na,K-ATPase as a receptor providing signal transduction inside the cell not only by changing the concentration of biologically significant cations but also using direct interaction of the enzyme with the protein-partners is discussed.