Cloning and expression of a rabbit cDNA encoding a serum-activated ethylisopropylamiloride-resistant epithelial Na+/H+ exchanger isoform (NHE-2)

Chung Ming Tse, Susan A. Levine, Chris H C Yun, Marshall H. Montrose, Peter J. Little, Jacques Pouyssegur, Mark Donowitz

Research output: Contribution to journalArticle

Abstract

A unique Na+/H+ exchanger isoform, NHE-2, was cloned and characterized. NHE-2 is a protein of 809 amino acids with a calculated size of 90,787. It exhibits overall amino acid identity of 50, 44, and 60% with other cloned mammalian Na+/H+ exchangers NHE-1, NHE-3, and NHE-4, respectively. Northern blot analysis of poly(A+) RNA isolated from rabbit ileum, kidney cortex, and kidney medulla using NHE-2 cDNA as a probe revealed messages of 5.2, 4.2, and 3.2 kilobases with relative abundance (in descending order) kidney medulla > kidney cortex > ileum. More detailed tissue distribution of message was performed by ribonuclease protection assay. NHE-2 was predominantly expressed in kidney, intestine, and adrenal gland with a small amount in skeletal muscle and trachea. Stable expression of NHE-2 in PS120 fibroblasts confirmed that NHE-2 is a functional Na+/H+ exchanger which is defined by amiloride-sensitive Na+-dependent alkalinization of acid-loaded cells. NHE-2 has the same Ki for amiloride inhibition as NHE-1 (1 μM) but is 25-fold more resistant to ethylisopropylamiloride inhibition than is NHE-1 (500 versus 20 nM). Like NHE-1, NHE-2 can be activated by serum. Expression of NHE-2 in a polarized human intestinal epithelial cell line, Caco-2 cells, results in functional expression of NHE-2 in the apical membrane. Thus, we conclude that NHE-2 is a candidate to be an apical membrane Na+/H+ exchanger in intestinal and renal epithelial cells.

Original languageEnglish (US)
Pages (from-to)11917-11924
Number of pages8
JournalJournal of Biological Chemistry
Volume268
Issue number16
StatePublished - Jun 5 1993

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Sodium-Hydrogen Antiporter
Cloning
Organism Cloning
Protein Isoforms
Complementary DNA
Kidney Medulla
Rabbits
Kidney Cortex
Amiloride
Serum
Ileum
Epithelial Cells
Membranes
Kidney
Amino Acids
Caco-2 Cells
Tissue Distribution
Fibroblasts
Ribonucleases
Adrenal Glands

ASJC Scopus subject areas

  • Biochemistry

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Cloning and expression of a rabbit cDNA encoding a serum-activated ethylisopropylamiloride-resistant epithelial Na+/H+ exchanger isoform (NHE-2). / Tse, Chung Ming; Levine, Susan A.; Yun, Chris H C; Montrose, Marshall H.; Little, Peter J.; Pouyssegur, Jacques; Donowitz, Mark.

In: Journal of Biological Chemistry, Vol. 268, No. 16, 05.06.1993, p. 11917-11924.

Research output: Contribution to journalArticle

Tse, Chung Ming ; Levine, Susan A. ; Yun, Chris H C ; Montrose, Marshall H. ; Little, Peter J. ; Pouyssegur, Jacques ; Donowitz, Mark. / Cloning and expression of a rabbit cDNA encoding a serum-activated ethylisopropylamiloride-resistant epithelial Na+/H+ exchanger isoform (NHE-2). In: Journal of Biological Chemistry. 1993 ; Vol. 268, No. 16. pp. 11917-11924.
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