Serine 77 in the PDZ domain of PICK1 is a protein kinase Cα phosphorylation site regulated by lipid membrane binding

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PICK1 (protein interacting with C kinase 1) contains an N-terminal protein binding PDZ domain and a C-terminal lipid binding BAR domain. PICK1 plays a key role in several physiological processes, including synaptic plasticity. However, little is known about the cellular mechanisms governing the activity of PICK1 itself. Here we show that PICK1 is a substrate in vitro both for PKCα (protein kinase Cα), as previously shown, and for CaMKIIα (Ca(2+)-calmodulin-dependent protein kinase IIα). By mutation of predicted phosphorylation sites, we identify Ser77 in the PDZ domain as a major phosphorylation site for PKCα. Mutation of Ser77 reduced the level of PKCα-mediated phosphorylation ~50%, whereas no reduction was observed upon mutation of seven other predicted sites. Addition of lipid vesicles increased the level of phosphorylation of Ser77 10-fold, indicating that lipid binding is critical for optimal phosphorylation. Binding of PKCα to the PICK1 PDZ domain was not required for phosphorylation, but a PDZ domain peptide ligand reduced the overall level of phosphorylation ~30%. The phosphomimic S77D reduced the extent of cytosolic clustering of eYFP-PICK1 in COS7 cells and thereby conceivably its lipid binding and/or polymerization capacity. We propose that PICK1 is phosphorylated at Ser77 by PKCα preferentially when bound to membrane vesicles and that this phosphorylation in turn modulates its cellular distribution.
Original languageEnglish
JournalBiochemistry
Volume51
Issue number2
Pages (from-to)586-96
Number of pages11
DOIs
Publication statusPublished - 17 Jan 2012

    Research areas

  • Amino Acid Substitution, Animals, Binding Sites, COS Cells, Calcium-Calmodulin-Dependent Protein Kinase Type 2, Carrier Proteins, Cell Membrane, Cercopithecus aethiops, Lipid Metabolism, Models, Molecular, Mutagenesis, Site-Directed, Mutation, Nuclear Proteins, PDZ Domains, Phosphorylation, Protein Kinase C-alpha, Protein Transport, Serine

ID: 46375150