Differential Activities of Protein Phosphatase Types 1 and 2A in Cytosolic and Participate Fractions from Rat Forebrain
- 1 April 1994
- journal article
- research article
- Published by Wiley in Journal of Neurochemistry
- Vol. 62 (4), 1552-1559
- https://doi.org/10.1046/j.1471-4159.1994.62041552.x
Abstract
The activities and concentrations of protein phosphates type 1 (PP1) and type 2A (PP2A) were compared in cytosol and particulate fractions of rat forebrain. Although the activity of PP2A was highest in the cytosol, immunoblot analysis with a PP2A-specific antibody showed that there were significant levels of the enzyme in the particulate fraction. There was no significant difference between the concentration of PP2A in the cytosol and particulate fractions such that the low activity of PP2A in the particulate fraction represents an inactivation of this form of the enzyme. Similar analysis in skeletal muscle, heart, and liver showed this finding was unique to the brain. Similarly, the majority of PP1 activity was recovered in the cytosol, but most PP1 enzyme was associated with the particulate fraction. Comparison with other tissues showed that the activities of PP1 in the particulate fractions were similar but that the forebrain contained significantly more enzyme than the other tissues. Thus, like PP2A it appears that the specific activity of PP1 in the particulate fraction of rat forebrain is much lower than that of the cytosol and of the particulate fractions of other tissues. Elution of PP1 and PP2A from membranes with 0.5 M NaCl plus 0.3% Triton X-100 resulted in severalfold activation of both enzymes. That the majority of PP1 and PP2A in rat forebrain are associated with membrane structures but in a low activity state suggests that novel regulatory mechanisms exist that have considerable and unique potential for activation of protein dephosphorylation.Keywords
This publication has 39 references indexed in Scilit:
- Synaptosomal amino acid release: Effect of inhibiting protein phosphatases with okadaic acidNeuroscience Letters, 1993
- Phosphorylation of the catalytic subunit of type‐1 protein phosphatase by the v‐abl tyrosine kinaseFEBS Letters, 1991
- Okadaic Acid-Induced Inhibition of B-50 Dephosphorylation by Presynaptic Membrane-Associated Protein PhosphatasesJournal of Neurochemistry, 1991
- The regulation and function of protein phosphatases in the brainMolecular Neurobiology, 1991
- Modulation of synaptosomal protein phosphorylation/dephosphorylation by calcium is antagonised by inhibition of protein phosphatases with okadaic acidNeuroscience Letters, 1991
- Regulation of protein phosphatase‐1G from rabbit skeletal muscleEuropean Journal of Biochemistry, 1989
- Glycogen-bound type-1 phosphatase: Isolation and dissociation of a complex containing undegraded G-subunitBiochemical and Biophysical Research Communications, 1989
- An improved procedure for identifying and quantitating protein phosphatases in mammalian tissuesFEBS Letters, 1989
- A second catalytic subunit of type‐2A protein phosphatase from rabbit skeletal muscleFEBS Letters, 1987
- Measurement of the potential activity of the type-1 and type-2 protein phosphatases in the crude tissue extractBiochemical and Biophysical Research Communications, 1985