Cl- channels in basolateral renal medullary membranes: VII. Characterization of the intracellular anion binding sites

Christopher J. Winters, W. Brian Reeves, Thomas E. Andreoli

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A unique property of basolateral membrane Cl- channels from the mTAL is that the Cl- concentration facing the intracellular aspects of these channels is a determinant of channel open time probability (P0). The K1/2 for maximal activation of P0 by Cl- facing intracellular domains of these channels is 10 m m Cl-. The present experiments evaluated the nature of these Cl--interactive sites. First, we found that the impermeant anion isethionate, when exposed to intracellular Cl- channel faces, could augment P0 with a K1/2 in the range of 10 m m isethionate without affecting conductance (gCl, pS). Second, pretreatment of the solutions facing the intracellular aspects of the channels with either 1 m m phenylglyoxal (PGO), an arginine-specific reagent, or the lysine/terminal amine reagent trinitrobenzene sulfonic acid (TNBS, 1 m m), prevented the activation of P0 usually seen when the Cl- concentration of solutions facing intracellular channel domains was raised from 2 to 50 m m. However, when the Cl- channel activity was increased by first raising the Cl- concentration bathing intracellular channel faces from 2 to 50 m m, subsequent addition of either PGO or TNBS to solutions bathing intracellular Cl- channel faces had no effect on P0. We conclude that the intracellular aspects of these Cl- channels contain Cl--interactive loci (termed [Cl]i) which are accessible to impermeant anions in intracellular fluids and which contain arginineand lysine-rich domains which can be inactivated, at low ambient Cl- or isethionate concentrations, by interactions with PGO or TNBS.

Original languageEnglish (US)
Pages (from-to)145-152
Number of pages8
JournalThe Journal of Membrane Biology
Issue number2
StatePublished - Aug 1 1993



  • Anion binding sites
  • Cl channels
  • Cl-interactive loci
  • PGO
  • TNBS

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Cell Biology

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