Phosphorylation of transglutaminase 2 by PKA at Ser216 creates 14-3-3 binding sites.
Transglutaminase 2 (TG2) is a multifunctional ubiquitous enzyme which is present in various cellular compartments and is subject to phosphorylation by PKA. To better understand the relevance of PKA induced phosphorylation of TG2, we performed pull-down assays using phosphorylated biotinylated-TG2(209-223) peptides spanning PKA induced phosphorylation sites as a bait. Subsequent analysis of pull-down protein by SDS-PAGE and LC/MS identified 14-3-3epsilon as the binding partner for TG2 which was further confirmed by immunoblotting with 14-3-3 specific antiserum. In contrast, non-phosphorylated and/or phosphorylation site substituted peptides fail to pull-down 14-3-3. Furthermore, we demonstrate that 14-3-3 co-immunoprecipitated with TG2 antiserum after activation of PKA from mouse embryonic fibroblasts (MEF)(TG2+/+) cells but not from MEF(TG2-/-) cells. In summary, we provide convincing evidence that phosphorylation of TG2 by PKA creates binding site(s) for 14-3-3 both in vitro and in vivo.
Mishra
Suresh
S
Department of Physiology and Internal Medicine, University of Manitoba, Winnipeg, Man., Canada R3E 0W3. mishra@cc.umanitoba.ca
Murphy
Liam J
LJ
D048948:14-3-3 Proteins / Q000276:immunology / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D015153:Blotting, Western; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D047468:Immunoprecipitation; D051379:Mice; D008969:Molecular Sequence Data; D010766:Phosphorylation; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D012694:Serine / Q000378:metabolism*; D011503:Transglutaminases / Q000378:metabolism*
D048948:14-3-3 Proteins; D012694:Serine; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D017868:Cyclic AMP-Dependent Protein Kinases; D019204:GTP-Binding Proteins