TY - JOUR

T1 - Serine 77 in the PDZ domain of PICK1 is a protein kinase Cα phosphorylation site regulated by lipid membrane binding

AU - Ammendrup-Johnsen, Ina

AU - Thorsen, Thor Seneca

AU - Gether, Ulrik

AU - Madsen, Kenneth Lindegaard

PY - 2012/1/17

Y1 - 2012/1/17

N2 - 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.

AB - 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.

KW - Amino Acid Substitution

KW - Animals

KW - Binding Sites

KW - COS Cells

KW - Calcium-Calmodulin-Dependent Protein Kinase Type 2

KW - Carrier Proteins

KW - Cell Membrane

KW - Cercopithecus aethiops

KW - Lipid Metabolism

KW - Models, Molecular

KW - Mutagenesis, Site-Directed

KW - Mutation

KW - Nuclear Proteins

KW - PDZ Domains

KW - Phosphorylation

KW - Protein Kinase C-alpha

KW - Protein Transport

KW - Serine

U2 - 10.1021/bi2014689

DO - 10.1021/bi2014689

M3 - Journal article

C2 - 22129425

VL - 51

SP - 586

EP - 596

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 2

ER -