TY - JOUR
T1 - A consensus sequence in the endothelin-B receptor second intracellular loop is required for NHE3 activation by endothelin-1
AU - Laghmani, Kamel
AU - Sakamoto, Aiji
AU - Yanagisawa, Masashi
AU - Preisig, Patricia A.
AU - Alpern, Robert J.
PY - 2005/4
Y1 - 2005/4
N2 - 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 (ETB) and not in cells expressing the endothelin-A (ETA) receptor. However, ET-1 causes similar patterns of protein tyrosine phosphorylation, adenylyl cyclase inhibition, and increases in cell [Ca2+] in ETA- and ET B-expressing OKP cells, implying that an additional mechanism is required for NHE3 stimulation by the ETB receptor. The present studies used ETA and ETB 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 ETA 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 ETB 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.
AB - 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 (ETB) and not in cells expressing the endothelin-A (ETA) receptor. However, ET-1 causes similar patterns of protein tyrosine phosphorylation, adenylyl cyclase inhibition, and increases in cell [Ca2+] in ETA- and ET B-expressing OKP cells, implying that an additional mechanism is required for NHE3 stimulation by the ETB receptor. The present studies used ETA and ETB 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 ETA 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 ETB 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.
KW - Endothelin-A/endothelin-B chimeras
KW - Opossum kidney cells
KW - Sodium/hydrogen antiporter activity
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U2 - 10.1152/ajprenal.00300.2004
DO - 10.1152/ajprenal.00300.2004
M3 - Article
C2 - 15598844
AN - SCOPUS:15044343273
SN - 1931-857X
VL - 288
SP - F732-F739
JO - American Journal of Physiology - Renal Physiology
JF - American Journal of Physiology - Renal Physiology
IS - 4 57-4
ER -