title: Microcystin affinity purification of plant protein phosphatases: PP1C, PP5 and a regulatory A-subunit of PP2A.
abstract: Proteins of approximately 35, 55 and 65kDa were purified from cauliflower extracts by microcystin-Sepharose chromatography and identified by amino acid sequencing as plant forms of protein (serine/threonine) phosphatase 1 (PP1) catalytic subunit, PP5 and a regulatory A-subunit of PP2A, respectively. Peptides that corresponded both to the tetratricopeptide (TPR) repeat and catalytic domains of PP5 were identified. Similar to mammalian PP5,the casein phosphatase activity of plant PP5 was activated >10-fold by arachidonic acid, with half-maximal stimulation occurring at approximately 100 microM lipid.
authors.affiliation: Medical Research Council Protein Phosphorylation Unit, Department of Biochemistry, University of Dundee, MSI/WTB Complex, Dundee, UK. smeek@bad.dundee.ac.uk
authors.forename: S
authors.initials: S
authors.lastname: Meek
authors.forename: N
authors.initials: N
authors.lastname: Morrice
authors.forename: C
authors.initials: C
authors.lastname: MacKintosh
mesh_terms: D000595:Amino Acid Sequence; D016718:Arachidonic Acid / Q000737:chemistry / Q000494:pharmacology; D002846:Chromatography, Affinity / Q000379:methods*; D002847:Chromatography, Agarose / Q000379:methods; D002852:Chromatography, Ion Exchange / Q000379:methods; D004789:Enzyme Activation / Q000187:drug effects; D019787:Linoleic Acid / Q000494:pharmacology; D052998:Microcystins; D008969:Molecular Sequence Data; D019814:Myristic Acid / Q000494:pharmacology; D009687:Nuclear Proteins / Q000187:drug effects / Q000302:isolation & purification* / Q000378:metabolism; D019301:Oleic Acid / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000737:chemistry / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000187:drug effects / Q000302:isolation & purification* / Q000378:metabolism; D010940:Plant Proteins / Q000302:isolation & purification*; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2; D017421:Sequence Analysis
chemical_list: D052998:Microcystins; D009687:Nuclear Proteins; D010456:Peptides, Cyclic; D010940:Plant Proteins; D019814:Myristic Acid; D016718:Arachidonic Acid; D019301:Oleic Acid; C078588:microcystin; D019787:Linoleic Acid; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2; C089641:protein phosphatase 5