Membrane localization is critical for activation of the PICK1 BAR domain.
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.
Madsen
Kenneth L
KL
Department of Neuroscience and Pharmacology, Molecular Neuropharmacology Group, Center for Pharmacogenomics, The Panum Institute, University of Copenhagen, DK-2200 Copenhagen N, Denmark.
Eriksen
Jacob
J
Milan-Lobo
Laura
L
Han
Daniel S
DS
Niv
Masha Y
MY
Ammendrup-Johnsen
Ina
I
Henriksen
Ulla
U
Bhatia
Vikram K
VK
Stamou
Dimitrios
D
Sitte
Harald H
HH
McMahon
Harvey T
HT
Weinstein
Harel
H
Gether
Ulrik
U
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
D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D008024:Ligands; D008055:Lipids; D009687:Nuclear Proteins; C498298:PICK1 protein, rat