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Title: A novel subtype of AP-1-binding motif within the palmitoylated trans-Golgi network/endosomal accessory protein Gadkin/gamma-BAR
Authors: Maritzen, Tanja ×
Schmidt, Michael R
Kukhtina, Viktoria
Higman, Victoria A
Strauss, Holger
Volkmer, Rudolf
Oschkinat, Hartmut
Dotti, Carlos
Haucke, Volker #
Issue Date: Feb-2010
Series Title: Journal of Biological Chemistry vol:285 issue:6 pages:4074-4086
Abstract: Membrane traffic between the trans-Golgi network (TGN) and endosomes is mediated in part by the assembly of clathrin-AP-1 adaptor complex-coated vesicles. This process involves multiple accessory proteins that directly bind to the ear domain of AP-1gamma via degenerate peptide motifs that conform to the consensus sequence diameterG(P/D/E)(diameter/L/M) (with diameter being a large hydrophobic amino acid). Recently, gamma-BAR (hereafter referred to as Gadkin for reasons explained below) has been identified as a novel AP-1 recruitment factor involved in AP-1-dependent endosomal trafficking of lysosomal enzymes. How precisely Gadkin interacts with membranes and with AP-1gamma has remained unclear. Here we show that Gadkin is an S-palmitoylated peripheral membrane protein that lacks stable tertiary structure. S-Palmitoylation is required for the recruitment of Gadkin to TGN/endosomal membranes but not for binding to AP-1. Furthermore, we identify a novel subtype of AP-1-binding motif within Gadkin that specifically associates with the gamma1-adaptin ear domain. Mutational inactivation of this novel type of motif, either alone or in combination with three more conventional AP-1gamma binding peptides, causes Gadkin to mislocalize to the plasma membrane and interferes with its ability to render AP-1 brefeldin A-resistant, indicating its physiological importance. Our studies thus unravel the molecular basis for Gadkin-mediated AP-1 recruitment to TGN/endosomal membranes and identify a novel subtype of the AP-1-binding motif.
URI: 
ISSN: 0021-9258
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Department of Human Genetics - miscellaneous
× corresponding author
# (joint) last author

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