Sodium/Hydrogen Exchanger 1 (NHE1)

The Na+/H+ antiporter is a ubiquitous membrane-bound enzyme involved in volume- and pH-regulation of vertebrate cells. It is inhibited by the non-specific diuretic drug amiloride and activated by a variety of signals including growth factors, mitogens, neurotransmitters, tumor promoters, and others.The gene was first disrupted in mouse fibroblasts. The lost function was then restored by transfection with human genomic DNA. Clones containing these specific human sequences were isolated. One genomic fragment was identified as an exon-coding sequence from the sodium-hydrogen ion antiporter gene by demonstration that it could complement antiporter deficiency in mouse cells; that it recognized an mRNA in cells expressing antiport activity but not in deficient cells; and that it was amplified in variants overexpressing antiport activity.