title: Differential effects of apolipoprotein E isoforms on phosphorylation at specific sites on tau by glycogen synthase kinase-3 beta identified by nano-electrospray mass spectrometry.
abstract: Previously published data have shown an allele-specific variation in the in vitro binding of apolipoprotein E (apoE) to tau, which prompted the hypothesis that apoE binding may protect tau from phosphorylation, apoE3 being more efficient than apoE4. We have, therefore, investigated the effects of apoE on tau phosphorylation in vitro by the proline-directed kinase, glycogen synthase kinase (GSK)-3 beta. The phosphopeptide maps of tau alone, of tau with apoE3 and of tau with apoE4 were very similar. When apoE2 was present a further four spots were evident. Additionally, of the 15 peptides phosphorylated in the presence or absence of apoE, subtle differences, some isoform-specific, in the relative amounts of phosphorylation were observed.
authors.affiliation: Department of Neuroscience, Institute of Psychiatry, London, UK. g.gibb@iop.kcl.ac.uk
authors.forename: G M
authors.initials: GM
authors.lastname: Gibb
authors.forename: J
authors.initials: J
authors.lastname: Pearce
authors.forename: J C
authors.initials: JC
authors.lastname: Betts
authors.forename: S
authors.initials: S
authors.lastname: Lovestone
authors.forename: M M
authors.initials: MM
authors.lastname: Hoffmann
authors.forename: W
authors.initials: W
authors.lastname: Maerz
authors.forename: W P
authors.initials: WP
authors.lastname: Blackstock
authors.forename: B H
authors.initials: BH
authors.lastname: Anderton
mesh_terms: D053329:Apolipoprotein E2; D053318:Apolipoprotein E3; D053327:Apolipoprotein E4; D001057:Apolipoproteins E / Q000235:genetics / Q000494:pharmacology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D038341:Glycogen Synthase Kinases; D006801:Humans; D010449:Peptide Mapping; D010750:Phosphoproteins / Q000737:chemistry; D010766:Phosphorylation; D011994:Recombinant Proteins / Q000737:chemistry / Q000494:pharmacology; D021241:Spectrometry, Mass, Electrospray Ionization; D014162:Transfection; D016875:tau Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D053329:Apolipoprotein E2; D053318:Apolipoprotein E3; D053327:Apolipoprotein E4; D001057:Apolipoproteins E; D010750:Phosphoproteins; D011994:Recombinant Proteins; D016875:tau Proteins; D038341:Glycogen Synthase Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases