Molecular cloning of a DEG/ENaC sodium channel cDNA from human testis.

The number of members of the recently defined DEG/ENaC sodium channel superfamily is increasing. Their importance in Na transport, taste perception, acid sensing, and mechanotransduction has been implicated. We have cloned a new member of this superfamily from human testis, which was named hTNaC1 (for human testis sodium channel 1). The hTNaC1 has 532 amino acid residues with two hydrophobic transmembrane domains. It has the highest identity (82%) with a rat H(+)-gated Na channel specific for sensory neurons (DRASIC) and a low identity (29%) with an epithelial isoform (alpha-ENaC) of this superfamily. Northern blot of human tissues revealed its selective expression in testis (7 kb) and absence in other tissues. The identification of a new member of Na channel specifically expressed in testis will expand the role of this channel family to the reproduction physiology.