Three subunits of the amiloride-sensitive Na+ channel, named α, β, and γ, have previously been cloned in rat colon. The human lung α chain (SCNN1A) has also been cloned and its gene localized on chromosome 12p13. We now report the molecular cloning of the human lung β (SCNN1B) and γ (SCNN1G) chains. In situ hybridization and pulsed-field electrophoresis experiments demonstrate that both genes are located within a common 400-kb fragment on chromosome 16p12-p13. Screening of the cDNA library reveals two forms of the β subunit that differ by the presence or absence of a 464-bp fragment in the 3′ region. A frameshift in the short form modifies the COOH terminal sequence of the corresponding protein. Since several similar frameshifts mutations have recently been reported in patients affected by a rare form of hypertension, the existence of COOH truncated forms of the β chain might be of physiological importance.
ASJC Scopus subject areas