Post-translational modifications of the regulatory subunits of cAMP-dependent protein kinases during G1/S progression.
During the G1/S transition of the cell cycle variations in the labelling by 8-N3-[32P]cAMP of the protein kinase A regulatory subunits RI and RII, used as a probe to monitor post-translational modifications that may regulate cAMP binding, were observed in synchronized HeLa cells. A decrease in 8-N3-[32P]cAMP labelling of RI, RII and RII phosphorylated by the catalytic subunit of PKA was correlated with the increased percentage of cells in phases G1. An increase in 8-N3-[32P]cAMP incorporated into the 54-kDa RII subunit during progression from G1 to S was correlated with an increase in intracellular cAMP. A transient increase in Mn-SOD activity was detected in cells arrested at the G1/S transition using two different techniques, suggesting that oxidative modulation of regulatory subunits by free radicals may modify cAMP binding sites during the cell cycle. Decreased photoaffinity labelling by 8-N3-[32P]cAMP of RI, RII and autophosphorylated RII subunits was found to be an inherent characteristic of PKA in the G1/S transition.
Yassenko
M
M
Unité 427/Inserm, faculté des sciences pharmaceutiques et biologiques de Paris, université René-Descartes, 75270 Paris, France. yassenko@pharmacie.univ-paris5.fr
Thérond
P
P
Evain-Brion
D
D
Keryer
G
G
D001386:Azides / Q000378:metabolism; D020134:Catalytic Domain; D002453:Cell Cycle; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000096:biosynthesis / Q000378:metabolism*; D005609:Free Radicals; D016193:G1 Phase; D006367:HeLa Cells; D006801:Humans; D019920:Photoaffinity Labels / Q000378:metabolism; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D016196:S Phase; D013329:Structure-Activity Relationship
D001386:Azides; D005609:Free Radicals; D019920:Photoaffinity Labels; C017042:8-azidoadenosine-3',5'-monophosphate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases