Point mutations in αbENaC regulate channel gating, ion selectivity, and sensitivity to amiloride

Catherine M. Fuller, Bakhram K. Berdiev, Vadim G. Shlyonsky, Iskander I. Ismailov, Dale J. Benos

Research output: Contribution to journalArticle

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Abstract

We have generated two site-directed mutants, K504E and K515E, in the α subunit of an amiloride-sensitive bovine epithelial Na+ channel, αbENaC. The region in which these mutations lie is in the large extracellular loop immediately before the second membrane-spanning domain (M2) of the protein. We have found that when membrane vesicles prepared from Xenopus oocytes expressing either K504E or K515E αbENaC are incorporated into planar lipid bilayers, the gating pattern, cation selectivity, and amiloride sensitivity of the resultant channel are all altered as compared to the wild-type protein. The mutated channels exhibit either a reduction or a complete lack of its characteristic burst-type behavior, significantly reduced Na+:K+ selectivity, and an approximately 10-fold decrease in the apparent inhibitory equilibrium dissociation constant (K(i)) for amiloride. Single-channel conductance for Na+ was not affected by either mutation. On the other hand, both K504E and K515E αbENaC mutants were significantly more permeable to K+, as compared to wild type. These observations identify a lysine-rich region between amino acid residues 495 and 516 of αbENaC as being important to the regulation of fundamental channel properties.

Original languageEnglish
Pages (from-to)1622-1632
Number of pages11
JournalBiophysical Journal
Volume72
Issue number4
Publication statusPublished - 1997
Externally publishedYes

Fingerprint

Ion Channel Gating
Amiloride
Point Mutation
Epithelial Sodium Channels
Mutation
Membranes
Lipid Bilayers
Xenopus
Lysine
Oocytes
Cations
Amino Acids
Proteins

ASJC Scopus subject areas

  • Biophysics

Cite this

Fuller, C. M., Berdiev, B. K., Shlyonsky, V. G., Ismailov, I. I., & Benos, D. J. (1997). Point mutations in αbENaC regulate channel gating, ion selectivity, and sensitivity to amiloride. Biophysical Journal, 72(4), 1622-1632.

Point mutations in αbENaC regulate channel gating, ion selectivity, and sensitivity to amiloride. / Fuller, Catherine M.; Berdiev, Bakhram K.; Shlyonsky, Vadim G.; Ismailov, Iskander I.; Benos, Dale J.

In: Biophysical Journal, Vol. 72, No. 4, 1997, p. 1622-1632.

Research output: Contribution to journalArticle

Fuller, CM, Berdiev, BK, Shlyonsky, VG, Ismailov, II & Benos, DJ 1997, 'Point mutations in αbENaC regulate channel gating, ion selectivity, and sensitivity to amiloride', Biophysical Journal, vol. 72, no. 4, pp. 1622-1632.
Fuller CM, Berdiev BK, Shlyonsky VG, Ismailov II, Benos DJ. Point mutations in αbENaC regulate channel gating, ion selectivity, and sensitivity to amiloride. Biophysical Journal. 1997;72(4):1622-1632.
Fuller, Catherine M. ; Berdiev, Bakhram K. ; Shlyonsky, Vadim G. ; Ismailov, Iskander I. ; Benos, Dale J. / Point mutations in αbENaC regulate channel gating, ion selectivity, and sensitivity to amiloride. In: Biophysical Journal. 1997 ; Vol. 72, No. 4. pp. 1622-1632.
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