title: Interplay between phosphorylation and palmitoylation mediates plasma membrane targeting and sorting of GAP43.
abstract: Phosphorylation and lipidation provide posttranslational mechanisms that contribute to the distribution of cytosolic proteins in growing nerve cells. The growth-associated protein GAP43 is susceptible to both phosphorylation and S-palmitoylation and is enriched in the tips of extending neurites. However, how phosphorylation and lipidation interplay to mediate sorting of GAP43 is unclear. Using a combination of biochemical, genetic, and imaging approaches, we show that palmitoylation is required for membrane association and that phosphorylation at Ser-41 directs palmitoylated GAP43 to the plasma membrane. Plasma membrane association decreased the diffusion constant fourfold in neuritic shafts. Sorting to the neuritic tip required palmitoylation and active transport and was increased by phosphorylation-mediated plasma membrane interaction. Vesicle tracking revealed transient association of a fraction of GAP43 with exocytic vesicles and motion at a fast axonal transport rate. Simulations confirmed that a combination of diffusion, dynamic plasma membrane interaction and active transport of a small fraction of GAP43 suffices for efficient sorting to growth cones. Our data demonstrate a complex interplay between phosphorylation and lipidation in mediating the localization of GAP43 in neuronal cells. Palmitoylation tags GAP43 for global sorting by piggybacking on exocytic vesicles, whereas phosphorylation locally regulates protein mobility and plasma membrane targeting of palmitoylated GAP43.
authors.affiliation: Department of Neurobiology, University of Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Gauthier-Kemper
authors.affiliation: Department of Neurobiology, University of Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Maxim
authors.initials: M
authors.lastname: Igaev
authors.affiliation: Department of Neurobiology, University of Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Frederik
authors.initials: F
authors.lastname: Sündermann
authors.affiliation: Department of Neurobiology, University of Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Dennis
authors.initials: D
authors.lastname: Janning
authors.affiliation: Department of Neurobiology, University of Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Brühmann
authors.affiliation: Department of Neurobiology, University of Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Moschner
authors.affiliation: Department of Experimental Physics, University of Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Reyher
authors.affiliation: Department of Biophysics, University of Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Junge
authors.affiliation: Department of Neurology, University of Bonn, 53127 Bonn, Germany.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Glebov
authors.affiliation: Department of Neurology, University of Bonn, 53127 Bonn, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Walter
authors.affiliation: Department of Neurobiology, University of Osnabrück, 49076 Osnabrück, Germany.
authors.forename: Lidia
authors.initials: L
authors.lastname: Bakota
authors.affiliation: Department of Neurobiology, University of Osnabrück, 49076 Osnabrück, Germany brandt@biologie.uni-osnabrueck.de.
authors.forename: Roland
authors.initials: R
authors.lastname: Brandt
mesh_terms: D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D002462:Cell Membrane / Q000378:metabolism*; D004058:Diffusion; D005089:Exocytosis; D019922:GAP-43 Protein / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D054878:Lipoylation; D008969:Molecular Sequence Data; D016501:Neurites / Q000378:metabolism; D016716:PC12 Cells / Q000378:metabolism; D010766:Phosphorylation; D021381:Protein Transport; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000378:metabolism
chemical_list: D019922:GAP-43 Protein; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D012694:Serine