Shrinkage activates a non-selective conductance: involvement of a
walker-motif protein and protein kinase c.
Nelson, Deborah J., Xiao-Ying Tien, Weiwen Xie, Thomas A. Brasitus,
Marcia A. Kaetzel, and John R. Dedman.
Departments of Medicine and *Neurology, University of Chicago,
Chicago, IL 60637, Department of Molecular and Cellular Physiology,
University of Cincinnati College of Medicine, Cincinnati, OH
45267
APStracts 2:0242C, 1995.
The ability of all cells to maintain their volume during an osmotic
challenge is dependent upon the regulated movement of salt and water
across the plasma membrane. We demonstrate the phosphorylation
-dependent gating of a nonselective conductance in Caco-2 cells during
cellular shrinkage. Intracellular application of exogenous purified
rat brain protein kinase C (PKC) resulted in the activation of a
current similar to that activated during shrinkage with a Na:Cl
permeability ratio of approximately 1.7:1. In order to prevent
possible PKC/shrinkage-dependent activation of CFTR, which is
expressed at high levels in Caco-2 cells, a functional anti-peptide
antibody, anti-CFTR505-511, was introduced into the cells via the
patch pipette. Anti-CFTR505-511, which is directed against the Walker
motif in the first nucleotide binding fold of CFTR, prevented the
PKC/shrinking-induced current activation. The peptide CFTR505-511
also induced current inhibition, suggesting the possible involvement
of a regulatory element in close proximity to the channel which
shares sequence homology with the first nucleotide binding fold of
CFTR and whose binding to the channel is required for channel gating.
Received 10 April 1995; accepted in final form 22 June 1995.
APS Manuscript Number C200-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.