A Novel Subtype of AP-1-binding Motif within the Palmitoylated trans-Golgi Network/Endosomal Accessory Protein Gadkin/gamma-BAR

Tanja Maritzen, Michael R. Schmidt, Viktoria Kukhtina, Victoria A. Higman, Holger Strauss, Rudolf Volkmer, Hartmut Oschkinat, Carlos G. Dotti, Volker Haucke*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

9 Citations (Scopus)

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-1 gamma via degenerate peptide motifs that conform to the consensus sequence empty setG(P/D/E)(empty set/L/M) (with empty set 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-1 gamma 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 gamma 1-adaptin ear domain. Mutational inactivation of this novel type of motif, either alone or in combination with three more conventional AP-1 gamma 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.

Original languageEnglish
Pages (from-to)4074-4086
Number of pages13
JournalJournal of Biological Chemistry
Volume285
Issue number6
DOIs
Publication statusPublished - 5 Feb 2010

Keywords

  • COMPLEX
  • TRAFFICKING
  • MEMBRANE
  • AP-1
  • CELLS
  • CLATHRIN
  • ENDOSOMES
  • DOMAINS
  • ENTHOPROTIN
  • EAR-BINDING MOTIF

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