title: Membrane localization is critical for activation of the PICK1 BAR domain.
abstract: The PSD-95/Discs-large/ZO-1 homology (PDZ) domain protein, protein interacting with C kinase 1 (PICK1) contains a C-terminal Bin/amphiphysin/Rvs (BAR) domain mediating recognition of curved membranes; however, the molecular mechanisms controlling the activity of this domain are poorly understood. In agreement with negative regulation of the BAR domain by the N-terminal PDZ domain, PICK1 distributed evenly in the cytoplasm, whereas truncation of the PDZ domain caused BAR domain-dependent redistribution to clusters colocalizing with markers of recycling endosomal compartments. A similar clustering was observed both upon truncation of a short putative alpha-helical segment in the linker between the PDZ and the BAR domains and upon coexpression of PICK1 with a transmembrane PDZ ligand, including the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor GluR2 subunit, the GluR2 C-terminus transferred to the single transmembrane protein Tac or the dopamine transporter C-terminus transferred to Tac. In contrast, transfer of the GluR2 C-terminus to cyan fluorescent protein, a cytosolic protein, did not elicit BAR domain-dependent clustering. Instead, localizing PICK1 to the membrane by introducing an N-terminal myristoylation site produced BAR domain-dependent, but ligand-independent, PICK1 clustering. The data support that in the absence of PDZ ligand, the PICK1 BAR domain is inhibited through a PDZ domain-dependent and linker-dependent mechanism. Moreover, they suggest that unmasking of the BAR domain's membrane-binding capacity is not a consequence of ligand binding to the PDZ domain per se but results from, and coincides with, recruitment of PICK1 to a membrane compartment.
authors.affiliation: Department of Neuroscience and Pharmacology, Molecular Neuropharmacology Group, Center for Pharmacogenomics, The Panum Institute, University of Copenhagen, DK-2200 Copenhagen N, Denmark.
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Madsen
authors.forename: Jacob
authors.initials: J
authors.lastname: Eriksen
authors.forename: Laura
authors.initials: L
authors.lastname: Milan-Lobo
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Han
authors.forename: Masha Y
authors.initials: MY
authors.lastname: Niv
authors.forename: Ina
authors.initials: I
authors.lastname: Ammendrup-Johnsen
authors.forename: Ulla
authors.initials: U
authors.lastname: Henriksen
authors.forename: Vikram K
authors.initials: VK
authors.lastname: Bhatia
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Stamou
authors.forename: Harald H
authors.initials: HH
authors.lastname: Sitte
authors.forename: Harvey T
authors.initials: HT
authors.lastname: McMahon
authors.forename: Harel
authors.initials: H
authors.lastname: Weinstein
authors.forename: Ulrik
authors.initials: U
authors.lastname: Gether
mesh_terms: D000818:Animals; D001692:Biological Transport; D019556:COS Cells; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002522:Chlorocebus aethiops; D003598:Cytoskeletal Proteins; D005786:Gene Expression Regulation; D006624:Hippocampus / Q000378:metabolism; D008024:Ligands; D008055:Lipids / Q000737:chemistry; D008954:Models, Biological; D009687:Nuclear Proteins / Q000378:metabolism*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D051381:Rats
chemical_list: D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D008024:Ligands; D008055:Lipids; D009687:Nuclear Proteins; C498298:PICK1 protein, rat