Protein kinase A activity is required for the budding of constitutive transport vesicles from the trans-Golgi network.
We have examined the role played by protein kinase A (PKA) in vesicle-mediated protein transport from the trans-Golgi network (TGN) to the cell surface. In vivo this transport step was inhibited by inhibitors of PKA catalytic subunits (C-PKA) such as the compound known as H89 and a myristoylated form of the inhibitory peptide sequence contained in the thermostable PKA inhibitor. Inhibition by H89 occurred at an early stage during the transfer of vesicular stomatitis virus G glycoprotein from the TGN to the cell surface. Reversal from this inhibition correlated with a transient increase in the number of free coated vesicles in the Golgi area. Vesicle budding from the TGN was studied in vitro using vesicular stomatitis virus-infected, permeabilized cells. Addition to this assay of C-PKA stimulated vesicle release while it was suppressed by PKA inhibitory peptide, H89, and antibody against C-PKA. Furthermore, vesicle release was decreased when PKA-depleted cytosol was used and restored by addition of C-PKA. These results indicate a regulatory role for PKA activity in the production of constitutive transport vesicles from the TGN.
Muñiz
M
M
Department of Cell Biology, Faculty of Biology, University of Seville, 41012 Seville, Spain.
Martín
M E
ME
Hidalgo
J
J
Velasco
A
A
D000818:Animals; D001692:Biological Transport; D015550:Cell Degranulation; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D003594:Cytoplasmic Granules / Q000502:physiology*; D006056:Golgi Apparatus / Q000502:physiology* / Q000648:ultrastructure*; D008854:Microscopy, Electron; D051381:Rats
D017868:Cyclic AMP-Dependent Protein Kinases