Agonist-induced translocation of gq/11 immunoreactivity directly
from plasma membrane in mdck cells.
Arthur, John M., Georgiann P. Collinsworth, Thomas W. Gettys and John
R. Raymond.
The University of Louisville_, Louisville, KY 40202 and The Medical
University of South Carolina&, Charleston, South Carolina 29425
APStracts 5:0217F, 1998.
Gs and Gq are both palmitoylated and both can move from a crude
membrane fraction to a soluble fraction in response to stimulation
with agonists. This response may be mediated through
depalmitoylation. Previous studies have not demonstrated that
endogenous G protein -subunits are released directly from plasma
membrane. We have examined the effect of agonist stimulation on the
location of Gq/11 immunoreactivity in MDCK cells. Bradykinin (BK, 0.1
M) caused Gq/11, but not Gi, to rapidly translocate from purified
plasma membranes to the supernatant. AlF and GTP also caused
translocation of Gq/11 immunoreactivity from purified plasma
membranes. BK caused translocation of Gq/11 immunoreactivity in
intact cells from the basal and lateral plasma membranes to an
intracellular compartment as assessed by confocal microscopy. Thus,
Gq/11 is released directly from the plasma membrane to an
intracellular location in response to activation by agonist and
direct activation of G proteins. G protein translocation may be a
mechanism for desensitization or for signaling specificity.
Received 7 May 1998; accepted in final form 10 December 1998.
APS Manuscript Number F108-8.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 18 December 1998