Cloning and functional expression of a new epithelial sodium channel δ subunit isoform differentially expressed in neurons of the human and monkey telencephalon

Epithelial sodium channel (ENaC) is a member of the ENaC/ degenerin family of amiloride-sensitive, non-voltage gated sodium ion channels. ENaC alpha, beta and gamma subunits are abundantly expressed in epithelial tissues, where they have been well characterized. An ENaC 6 subunit has also been described in the human nervous system, although its histological distribution pattern remains unexplored. We have now isolated a novel ENaC delta isoform (delta 2) from human brain and studied the expression pattern of both the known (delta 1) and the new (delta 2) isoforms in the human and monkey telencephalon. ENaC delta 2 is produced by a combination of alternative transcription start sites, a frame shift in exon 3 and alternative splicing of exon 4. It forms functional amiloride-sensitive sodium