Referenced in: none

Automatically associated channels: ClC4

Title: Cl channels in basolateral TAL membranes. XVII. Kinetic properties of mcClC-Ka, a basolateral CTAL Cl- channel.

Authors: C J Winters, T E Andreoli

Journal, date & volume: J. Membr. Biol., 2002 Apr 1 , 186, 159-64

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/12148842

Abstract
This paper describes the kinetics of Cl- flux through mcClC-Ka Cl- channels from basolateral membranes of mouse CTAL cells. We have cloned two separate but highly homologous Cl- channels, mmClC-Ka from cultured mouse MTAL cells and mcClC-Ka from cultured mouse CTAL cells. The mmClC-Ka and mcClC-Ka channels appear to mediate net Cl- absorption in the MTAL and CTAL, respectively. The kinetics of Cl- permeation through mmClC-Ka channels exhibit traditional criteria for a first-order process, including saturation kinetics. Thus mmClC-Ka channels operate functionally as if the channels were occupied by a single Cl- ion at any given time. In the present studies, we examined conductance-concentration relations in mcClC-Ka channels, and compared both mole-fraction effects and ion selectivity characteristics in mmClC-Ka and mcClC-Ka channels. In mcClC-Ka channels, we observed both self-block at high external Cl- concentrations and, at constant ionic strength, an anomalous mole-fraction effect using external solutions containing varying F-/Cl- concentrations. Neither effect was obtained in mmClC-Ka channels. These data are consistent with the possibility that Cl- permeation through mcClC-Ka channels involved multi-ion occupancy channels that expressed single-file behavior.