Regulation of renal Na(+)-H+ exchanger by cAMP-dependent protein kinase.
Octyl glucoside-extracted rabbit renal brush-border membrane (BBM) proteins were sequentially fractionated using anion exchange chromatography, and the fractions were tested for Na(+)-H+ exchange activity, amiloride sensitivity, and the effect of adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase (PKA) after reconstitution into artificial lipid vesicles. Compared with the initial protein extract, an anionic protein fraction eluting with 0.2-0.4 M NaCl (fraction B) demonstrated increased Na(+)-H+ exchange activity. Fraction B also demonstrated sensitivity to inhibition by amiloride but was not regulated by PKA. Co-reconstitution of fraction B with a BBM protein fraction highly enriched in a 42-kDa polypeptide restored the inhibitory response to PKA. These experiments suggest that, as assayed in a solubilized and reconstituted system, the Na(+)-H+ exchanger contains a dissociable PKA regulatory component, possibly a polypeptide of 42 kDa.
Weinman
E J
EJ
Department of Internal Medicine, University of Texas Medical School, Houston 77225.
Steplock
D
D
Bui
G
G
Yuan
N
N
Shenolikar
S
S
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001345:Autoradiography; D002352:Carrier Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000378:metabolism* / Q000648:ultrastructure; D008081:Liposomes / Q000378:metabolism; D008871:Microvilli / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000502:physiology*; D011506:Proteins / Q000378:metabolism; D012964:Sodium / Q000493:pharmacokinetics; D017923:Sodium-Hydrogen Exchangers
D002352:Carrier Proteins; D008081:Liposomes; D011506:Proteins; D017923:Sodium-Hydrogen Exchangers; D000584:Amiloride; D012964:Sodium; D011494:Protein Kinases