Interaction of the catalytic subunits of protein phosphatase-1 and 2A with inhibitor-1 and 2: a fluorescent study with sulfhydryl-specific pyrene maleimide.
The catalytic subunits of protein phosphatase-1 and 2A were covalently modified in their reactive sulfhydryl groups with N-(3-Pyrene) maleimide resulting in fluorescent labeling of the proteins to an extent of 0.85 and 0.9 mole dye/mole enzyme, respectively. The reaction of the sulfhydryl group led to the partial inactivation of both phosphatase-1 and 2A. Inhibitor-1 and inhibitor-2 increased markedly the fluorescence intensity of the dye-phosphatase-1 conjugate implying that the labeled enzyme retained its ability to bind these proteins. In contrast, inhibitor-1 or inhibitor-2 had no influence on the fluorescence of the dye-phosphatase-2A conjugate. No change in either the fluorescence intensity or polarization of labeled phosphatase-1 and 2A was observed in the presence of thiophosphorylase a, suggesting a lack of interaction of these enzyme forms with the substrate after modification of the reactive sulfhydryl group.
Csortos
C
C
Department of Medical Chemistry, University School of Medicine, Debrecen, Hungary.
Matkó
J
J
Erdödi
F
F
Gergely
P
P
D002352:Carrier Proteins; D004791:Enzyme Inhibitors / Q000378:metabolism*; D005456:Fluorescent Dyes; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D046911:Macromolecular Substances; D008301:Maleimides; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D011485:Protein Binding; D054645:Protein Phosphatase 1; D011506:Proteins / Q000378:metabolism*; D013438:Sulfhydryl Compounds; D013439:Sulfhydryl Reagents; D000097847:Protein Phosphatase Inhibitory Proteins
D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D047908:Intracellular Signaling Peptides and Proteins; D046911:Macromolecular Substances; D008301:Maleimides; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D011506:Proteins; D013438:Sulfhydryl Compounds; D013439:Sulfhydryl Reagents; C021042:protein phosphatase inhibitor-1; C024833:protein phosphatase inhibitor-2; D000097847:Protein Phosphatase Inhibitory Proteins; C003944:N-(3-pyrene)maleimide