Trimeric G proteins modulate the dynamic interaction of PKAII with the Golgi complex.
The Golgi complex represents a major subcellular location of protein kinase A (PKA) concentration in mammalian cells where it has been previously shown to be involved in vesicle-mediated protein transport processes. We have studied the factors that influence the interaction of PKA typeII subunits with the Golgi complex. In addition to the cytosol, both the catalytic (Calpha) and regulatory (RIIalpha) subunits of PKAII were detected at both sides of the Golgi stack, particularly in elements of the cis- and trans-Golgi networks. PKAII subunits, in contrast, were practically absent from the middle Golgi cisternae. Cell treatment with either brefeldin A, AlF(4-) or at low temperature induced PKAII dissociation from the Golgi complex and redistribution to the cytosol. This suggested the existence of a cycle of association/dissociation of PKAII holoenzyme to the Golgi. The interaction of purified RIIalpha with Golgi membranes was studied in vitro and found not to be affected by brefeldin A while it was sensitive to modulators of heterotrimeric G proteins such as AlF(4-), GTPgammaS, beta(gamma) subunits and mastoparan. RII(alphaa) binding was stimulated by recombinant, myristoylated Galpha(i3) subunit and inhibited by cAMP. Pretreatment of Golgi membranes with bacterial toxins known to catalyze ADP-ribosylation of selected Galpha subunits also modified RIIalpha binding. Taken together the data support a regulatory role for Golgi-associated Galpha proteins in PKAII recruitment from the cytosol.
Martín
M E
ME
Department of Cell Biology, Faculty of Biology, University of Seville, Spain.
Hidalgo
J
J
Vega
F M
FM
Velasco
A
A
D017607:Aluminum Compounds / Q000494:pharmacology; D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology; D019556:COS Cells; D002417:Cattle; D000242:Cyclic AMP / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000032:analysis / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005459:Fluorides / Q000494:pharmacology; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D020962:Heterotrimeric GTP-Binding Proteins / Q000502:physiology*; D036341:Intercellular Signaling Peptides and Proteins; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D008297:Male; D010455:Peptides; D011485:Protein Binding / Q000187:drug effects; D013696:Temperature; D014862:Wasp Venoms / Q000494:pharmacology
D017607:Aluminum Compounds; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D014862:Wasp Venoms; D020126:Brefeldin A; C050992:tetrafluoroaluminate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C037500:mastoparan; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D020962:Heterotrimeric GTP-Binding Proteins; D005459:Fluorides