Single-channel behavior of a purified epithelial Na+ channel subunit that binds amiloride.
作者： S. Sariban-Sohraby , M. Abramow , R. S. Fisher
DOI: 10.1152/AJPCELL.1992.263.5.C1111
关键词: Apical membrane 、 Epithelial sodium channel 、 Patch clamp 、 Biochemistry 、 Ion transporter 、 Ligand-gated ion channel 、 Transport inhibitor 、 Amiloride 、 Lipid bilayer 、 Chemistry 、 Biophysics
摘要: The apical membrane of high electrical resistance epithelia, which is selectively permeable to Na+, plays an essential role in the maintenance salt balance. Na+ entry from fluid into cells mediated by amiloride-blockable Na(+)-specific channels. channel protein, purified both amphibian and mammalian sources, composed several subunits, only one 150-kDa polypeptide, specifically binds transport inhibitor amiloride. goal present study was investigate whether isolated amiloride-binding subunit could conduct Na+. patch-clamp technique used polypeptide incorporated a lipid bilayer formed on tip glass pipette. Unitary conductance jumps averaged 4.8 pS at 100 mM Na2HPO4. Open times ranged 24 ms seconds. spent most time closed state. Channel gating were independent voltage between -60 +100 mV. Amiloride (0.1 microM) decreased mean open 98%. We conclude that conducts current may be sufficient for function whole channel.
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