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 in cluding the phosphorylation of the catalytic subunit of the enzyme by diffe rent protein kinases (PKA, PKC, and tyrosine kinase) and the interaction of the alpha -subunit with different proteins (Na,K-ATPase beta- and gamma -s ubunits, ankyrin, phosphoinositide-3 kinase, and AP-2 protein) and endogeno us digitalis-like factors are considered. Special attention is given to the search for possible protein-partners including melittin-like protein and t o the mechanism of enzyme regulation connected with the change of Na,K-ATPa se quaternary structure. A recently discovered role of Na,K-ATPase as a rec eptor providing signal transduction inside the cell not only by changing th e concentration of biologically significant cations but also using direct i nteraction of the enzyme with the protein-partners is discussed.