A consensus sequence in the endothelin-B receptor second intracellular loop is required for NHE3 activation by endothelin-1

Am J Physiol Renal Physiol. 2005 Apr;288(4):F732-9. doi: 10.1152/ajprenal.00300.2004. Epub 2004 Dec 14.

Abstract

Endothelin-1 (ET-1) increases the activity of Na(+)/H(+) exchanger 3 (NHE3), the major proximal tubule apical membrane Na(+)/H(+) antiporter. This effect is seen in opossum kidney (OKP) cells expressing the endothelin-B (ET(B)) and not in cells expressing the endothelin-A (ET(A)) receptor. However, ET-1 causes similar patterns of protein tyrosine phosphorylation, adenylyl cyclase inhibition, and increases in cell [Ca(2+)] in ET(A)- and ET(B)-expressing OKP cells, implying that an additional mechanism is required for NHE3 stimulation by the ET(B) receptor. The present studies used ET(A) and ET(B) receptor chimeras and site-directed mutagenesis to identify the ET receptor domains that mediate ET-1 regulation of NHE3 activity. We found that binding of ET-1 to the ET(A) receptor inhibits NHE3 activity, an effect for which the COOH-terminal tail is necessary and sufficient. ET-1 stimulation of NHE3 activity requires the COOH-terminal tail and the second intracellular loop of the ET(B) receptor. Within the second intracellular loop, a consensus sequence was identified, KXXXVPKXXXV, that is required for ET-1 stimulation of NHE3 activity. This sequence suggests binding of a homodimeric protein that mediates NHE3 stimulation.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cells, Cultured
  • Consensus Sequence
  • Endothelin-1 / metabolism*
  • Endothelin-1 / pharmacology
  • Humans
  • Kidney / cytology
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Opossums
  • Protein Structure, Tertiary
  • Receptor, Endothelin B / chemistry
  • Receptor, Endothelin B / genetics*
  • Receptor, Endothelin B / metabolism
  • Sodium-Hydrogen Exchanger 3
  • Sodium-Hydrogen Exchangers / metabolism*
  • Transfection

Substances

  • Endothelin-1
  • Receptor, Endothelin B
  • SLC9A3 protein, human
  • Sodium-Hydrogen Exchanger 3
  • Sodium-Hydrogen Exchangers