Phosphorylation of the α‐subunits of the Na+/K+‐ATPase from mammalian kidneys and Xenopus oocytes by cGMP‐dependent protein kinase results in stimulation of ATPase activity
Open Access
- 5 March 1999
- journal article
- research article
- Published by Wiley in European Journal of Biochemistry
- Vol. 260 (3) , 904-910
- https://doi.org/10.1046/j.1432-1327.1999.00237.x
Abstract
Phosphorylation of Na+/K+‐ATPase by cGMP‐dependent protein kinase (PKG) has been studied in enzymes purified from pig, dog, sheep and rat kidneys, and in Xenopus oocytes. PKG phosphorylates the α‐subunits of all animal species investigated. Phosphorylation of the β‐subunit was not observed. The stoichiometry of phosphorylation estimated for pig, sheep and dog renal Na+/K+‐ATPase is 3.5, 2.2 and 2.1 mol Pi per mol α‐subunit, respectively. Proteolytic fingerprinting of the pig α1‐subunits phosphorylated by PKG using specific antibodies raised against N‐terminus or C‐terminus reveals that phosphorylation sites are located within the intracellular loop of the α‐subunit between the 35 kDa N‐terminal and 27 kDa C‐terminal fragments. Phosphorylation sites within the α1‐subunit of the purified Na+/K+‐ATPase do not appear to be easily accessible for PKG since incorporation of Pi requires 0.2% of Triton X‐100. Administration of cGMP and PKG in the presence of 5 mm ATP, which prevents inactivation of the Na+/K+‐ATPase by detergent, leads to stimulation of hydrolytic activity by 61%. Administration of 50 µm of cGMP or dbcGMP in yolk‐free homogenates of Xenopus oocytes leads to stimulation of ouabain‐dependent ATPase activity by 130–198% and to incorporation of 33P into the α‐subunit without the detergent. Hence, PKG plays regulatory role in active transmembraneous transport of Na+ and K+ via phosphorylation of the catalytic subunit of the Na+/K+‐ATPase.Keywords
This publication has 31 references indexed in Scilit:
- Diversity of Regulatory Phosphorylation of the Na+/K+-ATPase from Mammalian Kidneys and XenopusOocytes by Protein Kinases: Characterization of the Phosphorylation Site for Protein Kinase CCellular Physiology and Biochemistry, 1997
- Regulation of sodium‐potassium‐adenosine‐triphosphatase activity by extracellular guanosine 3′,5′‐cyclic monophosphate in rat kidneyActa Physiologica Scandinavica, 1996
- Arginine 75 in the Pseudosubstrate Sequence of Type Iβ cGMPdependent Protein Kinase Is Critical for Autoinhibition, Although Autophosphorylated Serine 63 Is Outside This SequencePublished by Elsevier ,1996
- The cellular Na+ pump as a site of action for carbon monoxide and glutamate: A mechanism for long-term modulation of cellular activityNeuron, 1995
- Epitope mapping by amino‐acid‐sequence‐specific antibodies reveals that both ends of the α subunit of Na+/K+‐ATPase are located on the cytoplasmic side of the membraneEuropean Journal of Biochemistry, 1991
- Activation of protein kinase C by phorbol ester induces downregulation of the Na+/K+-ATPase in oocytes ofXenopus laevisThe Journal of Membrane Biology, 1990
- Autophosphorylation of Protein Kinase C at Three Separated Regions of Its Primary SequenceScience, 1990
- Kinetics of phosphorylation of Na+K+-ATPase by protein kinase CBiochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1990
- Tryptic and chymotryptic cleavage sites in sequence of α-subunit of (Na+ + K+)-ATPase from outer medulla of mammalian kidneyBiochimica et Biophysica Acta (BBA) - Biomembranes, 1986
- Sensitivity of the (Na+ + K+)-ATPase to state-dependent inhibitorsBiochimica et Biophysica Acta (BBA) - Biomembranes, 1980