TY - JOUR
T1 - Interactions between subunits of the human epithelial sodium channel
AU - Adams, Christopher M.
AU - Snyder, Peter M.
AU - Welsh, Michael J.
PY - 1997
Y1 - 1997
N2 - The human epithelial sodium channel (hENaC) mediates Na+ transport across the apical membrane of epithelia, and mutations in hENaC result in hypertensive and salt-wasting diseases. In heterologous expression systems, maximal hENaC function requires co-expression of three homologous proteins, the α, β, and γhENaC subunits, suggesting that hENaC subunits interact to form a multimeric channel complex. Using a co-immunoprecipitation assay, we found that hENaC subunits associated tightly to form homo- and heteromeric complexes and that the association between subunits occurred early in channel biosynthesis. Deletion analysis of γhENaC revealed that the N terminus was sufficient but not necessary for co-precipitation of αhENaC, and that both the N terminus and the second transmembrane segment (M2) were required for γ subunit function. The biochemical studies were supported by functional studies. Co-expression of γ subunits lacking M2 with full-length hENaC subunits revealed an inhibitory effect on hENaC channel function that appeared to be mediated by the cytoplasmic N terminus of γ, and was consistent with the assembly of nonfunctional subunits into the channel complex. We conclude that the N terminus of γhENaC is involved in channel assembly.
AB - The human epithelial sodium channel (hENaC) mediates Na+ transport across the apical membrane of epithelia, and mutations in hENaC result in hypertensive and salt-wasting diseases. In heterologous expression systems, maximal hENaC function requires co-expression of three homologous proteins, the α, β, and γhENaC subunits, suggesting that hENaC subunits interact to form a multimeric channel complex. Using a co-immunoprecipitation assay, we found that hENaC subunits associated tightly to form homo- and heteromeric complexes and that the association between subunits occurred early in channel biosynthesis. Deletion analysis of γhENaC revealed that the N terminus was sufficient but not necessary for co-precipitation of αhENaC, and that both the N terminus and the second transmembrane segment (M2) were required for γ subunit function. The biochemical studies were supported by functional studies. Co-expression of γ subunits lacking M2 with full-length hENaC subunits revealed an inhibitory effect on hENaC channel function that appeared to be mediated by the cytoplasmic N terminus of γ, and was consistent with the assembly of nonfunctional subunits into the channel complex. We conclude that the N terminus of γhENaC is involved in channel assembly.
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U2 - 10.1074/jbc.272.43.27295
DO - 10.1074/jbc.272.43.27295
M3 - Article
C2 - 9341177
AN - SCOPUS:0030854398
SN - 0021-9258
VL - 272
SP - 27295
EP - 27300
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 43
ER -