Jm. Arthur et al., Agonist-induced translocation of G(q/11)alpha immunoreactivity directly from plasma membrane in MDCK cells, AM J P-REN, 45(4), 1999, pp. F528-F534
Both G(s)alpha and G(q)alpha are palmitoylated and both can move from a cru
de 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 guanine nucleotide-binding re
gulatory protein (G protein) alpha-subunits are released directly from the
plasma membrane. We have examined the effect of agonist stimulation on the
location of G(q/11)alpha immunoreactivity in Madin-Darby canine kidney (MDC
K) cells. Bradykinin (BK; 0.1 mu M) caused G(q/11)alpha, but not G(i)alpha,
to rapidly translocate from purified plasma membranes to the supernatant.
AlF and GTP also caused translocation of G(q/11)alpha immunoreactivity from
purified plasma membranes. BK caused translocation of G(q/11)alpha immunor
eactivity in intact cells from the basal and lateral plasma membranes to an
intracellular compartment as assessed by confocal microscopy. Thus G(q/11)
alpha is released directly from the plasma membrane to an intracellular loc
ation in response to activation by an agonist and direct activation of G pr
oteins. G protein translocation may be a mechanism for desensitization or f
or signaling specificity.