This Article Full Text Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Chibalin, A. V. Articles by Zierath, J. R. Search for Related Content PubMed PubMed Citation Articles by Chibalin, A. V. Articles by Zierath, J. R.

Insulin- and Glucose-Induced Phosphorylation of the Na⁺,K⁺-Adenosine Triphosphatase -Subunits in Rat Skeletal Muscle

Department of Clinical Physiology (A.V.C., J.W.R., H.W.-H., J.R.Z.), Karolinska Hospital, 171 76 Stockholm, Sweden; Department of Physiology and Pharmacology (A.V.C., J.W.R., E.F., H.W.-H., J.R.Z.), Karolinska Institute, 171 77 Stockholm, Sweden; Ludwig Institute for Cancer Research (M.V.K.), 751 24 Uppsala, Sweden; and Division de Néphrologie (E.F.), Hôpital Cantonal Universitaire, 1211 Genève 4, Switzerland

Address all correspondence and requests for reprints to: Alexander V. Chibalin, Ph.D., Department of Clinical Physiology, Karolinska Hospital M1:02, 171 76, Stockholm, Sweden.

Phosphorylation of the -subunits of Na⁺,K⁺-adenosine triphosphatase in response to insulin, high extracellular glucose concentration, and phorbol 12-myristate 13-acetate was investigated in isolated rat soleus muscle. All three stimuli increased -subunit phosphorylation approximately 3-fold. Phorbol 12-myristate 13-acetate- and high glucose-induced phosphorylation of the -subunit was completely abolished by the PKC inhibitor GF109203X, whereas insulin-stimulated phosphorylation was only partially reduced. Notably, insulin stimulation resulted in phosphorylation of the -subunit on serine, threonine, and tyrosine residues, whereas high extracellular glucose or phorbol 12-myristate 13-acetate stimulation mediated phosphorylation only on serine and threonine residues. Insulin stimulation resulted in translocation of Na⁺,K⁺-adenosine triphosphatase ₂-subunit to the plasma membrane and increased Na⁺,K⁺-adenosine triphosphatase activity in the same membrane fraction. High glucose had no effect on -subunits distribution. Immunoprecipitation with antiphosphotyrosine antibody and subsequent Western blot analysis with anti-₁- and -₂-subunit antibodies revealed that both ₁- and ₂-subunit isoforms underwent phosphorylation on tyrosine residues in response to insulin, although with different time course and magnitude. Thus, we show that insulin-stimulated phosphorylation of Na⁺,K⁺-adenosine triphosphatase -subunit occurs via a PKC- and tyrosine kinase-dependent mechanism, whereas high glucose-induced phosphorylation is only PKC-dependent. Phosphorylation of Na⁺,K⁺-adenosine triphosphatase -subunits may be involved in regulation of Na⁺,K⁺-adenosine triphosphatase activity by insulin or high extracellular glucose in skeletal muscle.