CAMP-mediated inhibition of the renal brush border membrane Na+-H+ exchanger requires a dissociable phosphoprotein cofactor

J Clin Invest. 1993 Oct;92(4):1781-6. doi: 10.1172/JCI116767.


Prior studies have suggested that protein kinase A (PKA)-mediated inhibition of the rabbit renal brush border membrane (BBM) Na(+)-H+ exchanger involves a regulatory protein that is distinct from the transporter. This putative regulatory protein was purified by column chromatography and SDS-PAGE, and a partial primary amino acid sequence was determined. An affinity-purified polyclonal antibody to a synthetic peptide representing a sequence of the protein recognized a polypeptide of 55 kD in BBM but not in basolateral membrane. The antibody immunoprecipitated a PKA substrate of a similar molecular mass from detergent-solubilized BBM proteins. When assayed after reconstitution, PKA in the presence of ATP and Mg2+ did not inhibit Na(+)-H+ exchange transport in a fraction of solubilized BBM proteins eluting from an anion exchange column between 0.2 and 0.4 M NaCl (fraction B). Coreconstitution of fraction B with the immunoprecipitated 55-kD protein restored the inhibitory effect of PKA (change = 42%, P < 0.05). By contrast, Na(+)-H+ exchange transport in total solubilized BBM proteins was inhibited 25% (P < 0.05) by PKA, ATP, and Mg2+. This effect was abolished by immunodepletion of the cAMP regulatory protein (change = +5%, P = NS). These findings provide evidence that the regulation of renal BBM Na(+)-H+ exchange transport by PKA is affected by repletion and depletion of a specific protein. This suggests that PKA-mediated inhibition of the renal BBM Na(+)-H+ exchanger requires participation of a regulatory protein that is distinct from the transporter itself.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Blotting, Western
  • Cyclic AMP / pharmacology*
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Electrophoresis, Polyacrylamide Gel
  • Kidney / metabolism*
  • Liposomes / metabolism
  • Membrane Proteins / chemistry
  • Membrane Proteins / isolation & purification
  • Membrane Proteins / metabolism*
  • Microvilli / metabolism*
  • Molecular Sequence Data
  • Molecular Weight
  • Phosphoproteins / chemistry
  • Phosphoproteins / isolation & purification
  • Phosphoproteins / metabolism*
  • Proteolipids / metabolism
  • Rabbits
  • Sequence Homology, Amino Acid
  • Sodium-Hydrogen Exchangers / antagonists & inhibitors
  • Sodium-Hydrogen Exchangers / drug effects
  • Sodium-Hydrogen Exchangers / metabolism*
  • Transducin / chemistry


  • Liposomes
  • Membrane Proteins
  • Phosphoproteins
  • Proteolipids
  • Sodium-Hydrogen Exchangers
  • proteoliposomes
  • Cyclic AMP
  • Cyclic AMP-Dependent Protein Kinases
  • Transducin