CAMP-mediated inhibition of the epithelial brush border Na+/H+ exchanger, NHE3, requires an associated regulatory protein.

ABSTRACT: NHE3 is the Na+/H+ exchanger located on the intestinal and renal brush border membrane, where it functions in transepithelial Na+ absorption. The brush border Na+ absorptive process is acutely inhibited by activation of cAMP-dependent protein kinase, but the molecular mechanism of this inhibitory effect is poorly understood. We have identified two regulatory proteins, E3KARP and NHERF, that interact with NHE3 to enable cAMP to inhibit NHE3. The two regulatory proteins are structurally related, sharing approximately 50% identity in amino acid sequences. It has been previously shown that when NHE3 is transfected into PS120 fibroblasts or Caco-2 cells, cAMP failed to inhibit NHE3 activity. Northern blot analysis showed that both PS120 and Caco-2 cells lacked the expression of both E3KARP and

SUBMITTER: Yun CH 

PROVIDER: S-EPMC20313 | biostudies-literature | 1997 Apr

REPOSITORIES: biostudies-literature