Characterization of a protein cofactor that mediates protein kinase A regulation of the renal brush border membrane Na(+)-H+ exchanger.

Published

Journal Article

Activation of cAMP-dependent protein kinase A inhibits the renal proximal tubule brush border membrane Na(+)-H+ exchanger by a process involving participation of a regulatory cofactor (NHE-RF) that is distinct from the transporter itself. Recent studies from this laboratory reported a partial amino acid sequence of this putative cofactor (Weinman, E. J., D. H. Steplock, and S. Shenolikar. 1993. J. Clin. Invest. 92:1781-1786). The present experiments detail the structure of the NHE-RF protein as determined from molecular cloning studies. A codon-biased oligonucleotide probe to a portion of the amino acid sequence of the putative cofactor was used to isolate a 1.9-kb cDNA from a rabbit renal library. The encoded protein is 358 amino acids in length and is rich in proline residues. Search of existing data bases indicates that NHE-RF is a unique protein. Using a reticulocyte lysate, the cDNA translated a product of approximately 44 kD, which was recognized by an affinity-purified polyclonal antibody to NHE-RF. Potential phosphorylation sites for protein kinase A are present. The mRNA for the protein is expressed in kidney, proximal small intestine, and liver. Reverse transcription/PCR studies in the kidney indicate the presence of mRNA for NHE-RF in several distinct nephron segments including the proximal tubule.

Full Text

Duke Authors

Cited Authors

  • Weinman, EJ; Steplock, D; Wang, Y; Shenolikar, S

Published Date

  • May 1995

Published In

Volume / Issue

  • 95 / 5

Start / End Page

  • 2143 - 2149

PubMed ID

  • 7738182

Pubmed Central ID

  • 7738182

International Standard Serial Number (ISSN)

  • 0021-9738

Digital Object Identifier (DOI)

  • 10.1172/JCI117903

Language

  • eng

Conference Location

  • United States