Phosphorylation of the conditioning-associated GTP-binding protein cp20 by protein kinase C.
The phosphorylation state of cp20, a low molecular weight membrane-associated GTP-binding protein, was previously shown to increase two- to threefold 24 h after associative conditioning. Here, cp20 is shown to be phosphorylated by protein kinase C (PKC) in vitro. Pronounced differences in activity were observed with the three major isoforms of PKC, whereas casein kinase, calcium/calmodulin-dependent protein kinase II, and cyclic AMP-dependent protein kinase produced no detectable phosphorylation of cp20. Phosphorylation of cp20 had no effect on its GTPase or GTP-binding activity but caused a translocation of cp20 from cytosol to the nuclei/mitochondrial particulate fraction. These results suggest that the increase in phosphorylation of cp20 after conditioning may be due to PKC.
Nelson
T J
TJ
Laboratory of Adaptive Systems, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892-4124, USA.
Alkon
D L
DL
D000818:Animals; D001692:Biological Transport; D003213:Conditioning, Psychological / Q000502:physiology*; D049832:Decapodiformes; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D020559:Monomeric GTP-Binding Proteins; D009899:Optic Lobe, Nonmammalian / Q000378:metabolism / Q000648:ultrastructure; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D014018:Tissue Distribution
D007527:Isoenzymes; D010750:Phosphoproteins; D011493:Protein Kinase C; D019204:GTP-Binding Proteins; D020559:Monomeric GTP-Binding Proteins