Rabbit kidney expresses a transcript that is similar to the human growth-factor-activatable Na+/H+ exchanger. PCR and library screening were used to clone overlapping 2.5 kb, 1.4 kb, and 1.8 kb cDNAs that together contain the entire coding region (2448 bp) and 5' untranslated region (726 bp) and part of the 3' untranslated region (128 bp) of a rabbit renal Na+/H+ exchanger transcript. The nucleotide and inferred amino acid sequences are highly conserved between rabbit and human (88% nucleotide identity, 95% amino acid identity). In rabbit, the transcript is expressed in both epithelial and non-epithelial tissues, with highest expression in stomach, brain, kidney, lung and ileum, and minimal expression in liver and skeletal muscle.