Dephosphorylation of B-50 in synaptic plasma membranes
| Autor: | Michael R. Pisano, Henk Zwiers, L.H. Schrama, Willem Hendrik Gispen, Linda A. Dokas |
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| Rok vydání: | 1990 |
| Předmět: |
Male
GTP' Phosphatase Nerve Tissue Proteins Biology Dephosphorylation chemistry.chemical_compound Adenosine Triphosphate GAP-43 Protein medicine Phosphoprotein Phosphatases Animals Enzyme Inhibitors Phosphorylation Cerebral Cortex Membrane Glycoproteins Kinase General Neuroscience Leupeptin Rats Inbred Strains Phosphoproteins Adenosine Rats Membrane Biochemistry chemistry medicine.drug Synaptosomes |
| Zdroj: | Brain research bulletin. 24(3) |
| ISSN: | 0361-9230 |
| Popis: | Synaptic plasma membranes from rat brain cortex possess intrinsic ability to dephosphorylate the endogenous protein B-50. At low concentrations of [γ-32P]ATP, B-50 phosphorylation in synaptic membranes is maximal at 30 seconds, followed by dephosphorylation for an additional 60 minutes. The dephosphorylation of 32P-labeled B-50 is not sensitive to the protease inhibitor leupeptin and not correlated with a loss of the B-50 content of synaptic membranes as measured with immunoblot analysis. Dephosphorylation of membrane-associated B-50 is stimulated to a small extent by Mg2+ but not by Ca2+. Heat-stable protein phosphatase inhibitors prevent dephosphorylation of 32P-labeled B-50. Dephosphorylation of B-50 in synaptic membranes is stimulated by ATP, ADP, or adenosine 5′-O-thiotriphosphate, but not by adenine, adenosine, other adenine or guanine nucleotides, nonhydrolyzable analogs of ATP or GTP, nor by adenosine 5′-O-(2-thiodiphosphate). B-50, phosphorylated by exogenous protein kinase C and purified to homogeneity, has been used as a substrate to follow the purification of B-50 phosphatase activity. B-50 phosphatase activity can be solubilized from synaptic membranes with 0.5% Triton X-100 and 75 mM KCl. Chromatography of the extract on DEAE-cellulose yields enhanced B-50 phosphatase activity. |
| Databáze: | OpenAIRE |
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