Agonist-induced translocation of Gq/11alpha immunoreactivity directly from plasma membrane in MDCK cells.
Both Gsalpha and Gqalpha are 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 guanine nucleotide-binding regulatory protein (G protein) alpha-subunits are released directly from the plasma membrane. We have examined the effect of agonist stimulation on the location of Gq/11alpha immunoreactivity in Madin-Darby canine kidney (MDCK) cells. Bradykinin (BK; 0.1 microM) caused Gq/11alpha, but not Gialpha, to rapidly translocate from purified plasma membranes to the supernatant. AlF and GTP also caused translocation of Gq/11alpha immunoreactivity from purified plasma membranes. BK caused translocation of Gq/11alpha immunoreactivity in intact cells from the basal and lateral plasma membranes to an intracellular compartment as assessed by confocal microscopy. Thus Gq/11alpha is released directly from the plasma membrane to an intracellular location in response to activation by an agonist and direct activation of G proteins. G protein translocation may be a mechanism for desensitization or for signaling specificity.
Arthur
J M
JM
University of Louisville, Louisville, Kentucky 40202, USA. jarthur@kdp01.kdp-baptist.louisville.edu
Collinsworth
G P
GP
Gettys
T W
TW
Raymond
J R
JR
D017607:Aluminum Compounds / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D001920:Bradykinin / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004285:Dogs; D005455:Fluorescent Antibody Technique; D005459:Fluorides / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000819:agonists* / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000494:pharmacology; D007668:Kidney / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D018613:Microscopy, Confocal
D017607:Aluminum Compounds; D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins; D005459:Fluorides; D001920:Bradykinin; C032311:aluminum fluoride