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Membrane topology of the epithelial sodium channel in intact cells
Journal article

Membrane topology of the epithelial sodium channel in intact cells

  • Canessa, C. M. Institut de Pharmacologie et de Toxicologie, Universite de Lausanne,Switzerland.
  • Merillat, A. M. Institut de Pharmacologie et de Toxicologie, Universite de Lausanne,Switzerland.
  • Rossier, B. C. Institut de Pharmacologie et de Toxicologie, Universite de Lausanne,Switzerland.
Published in:
  • American Journal of Physiology-Cell Physiology. - American Physiological Society. - 1994, vol. 267, no. 6, p. C1682-C1690
Cell Biology
Physiology
English The highly selective amiloride-sensitive epithelial sodium channel is formed of three homologous subunits termed alpha-, beta-, and gamma-rENaC. Each subunit has two putative transmembrane domains (M1 and M2), yielding a protein with a large (approximately 50 kDa) hydrophilic loop (between M1 and M2) and short hydrophilic NH2- and COOH-termini (9 and 10 kDa). All three subunits are glycosylated in a cell-free translation assay, demonstrating that they share in vitro a common pattern of membrane insertion. The membrane topology of the alpha-rENaC subunit in intact cells was studied in Xenopus laevis oocytes. We demonstrate that 1) all six potential N-linked glycosylation sites (N190, N259, N320, N339, N424, and N538) of the large hydrophilic loop are used in intact cells; 2) the glycosylation of alpha-rENaC does not play a significant role in the functional expression of the channel; and 3) the two hydrophobic domains M1 (A109-F131) and M2 (S588-L612) serve in intact cells as start- and stop-transfer signals, respectively. We conclude that alpha-rENaC spans the membrane twice with the short NH2- and COOH-terminal ends on the cytoplasmic side and a large hydrophilic loop in the extracellular space.
Language
  • English
Open access status
closed
Identifiers
Persistent URL
https://sonar.ch/global/documents/144971
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