title: Non-microtubular localizations of microtubule-associated protein 6 (MAP6).
abstract: MAP6 proteins (MAP6s), which include MAP6-N (also called Stable Tubule Only Polypeptide, or STOP) and MAP6d1 (MAP6 domain-containing protein 1, also called STOP-Like protein 21 kD, or SL21), bind to and stabilize microtubules. MAP6 deletion in mice severely alters integrated brain functions and is associated with synaptic defects, suggesting that MAP6s may also have alternative cellular roles. MAP6s reportedly associate with the Golgi apparatus through palmitoylation of their N-terminal domain, and specific isoforms have been shown to bind actin. Here, we use heterologous systems to investigate several biochemical properties of MAP6 proteins. We demonstrate that the three N-terminal cysteines of MAP6d1 are palmitoylated by a subset of DHHC-type palmitoylating enzymes. Analysis of the subcellular localization of palmitoylated MAP6d1, including electron microscopic analysis, reveals possible localization to the Golgi and the plasma membrane but no association with the endoplasmic reticulum. Moreover, we observed localization of MAP6d1 to mitochondria, which requires the N-terminus of the protein but does not require palmitoylation. We show that endogenous MAP6d1 localized at mitochondria in mature mice neurons as well as at the outer membrane and in the intermembrane space of purified mouse mitochondria. Last, we found that MAP6d1 can multimerize via a microtubule-binding module. Interestingly, most of these properties of MAP6d1 are shared by MAP6-N. Together, these results describe several properties of MAP6 proteins, including their intercellular localization and multimerization activity, which may be relevant to neuronal differentiation and synaptic functions.
authors.affiliation: Inserm, U836, Physiopathologie du cytosquelette, BP170, Grenoble, France; University Grenoble Alpes, Grenoble Institut des Neurosciences, BP170, Grenoble, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Gory-Fauré
authors.affiliation: Inserm, U836, Physiopathologie du cytosquelette, BP170, Grenoble, France; University Grenoble Alpes, Grenoble Institut des Neurosciences, BP170, Grenoble, France.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Windscheid
authors.affiliation: Inserm, U836, Physiopathologie du cytosquelette, BP170, Grenoble, France; University Grenoble Alpes, Grenoble Institut des Neurosciences, BP170, Grenoble, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Brocard
authors.affiliation: Department of Cell Biology, University of Geneva, Sciences III, Geneva, Switzerland.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Montessuit
authors.affiliation: Division of Membrane Physiology, Department of Cell Physiology, National Institute for Physiological Sciences, Aichi, Japan.
authors.forename: Ryouhei
authors.initials: R
authors.lastname: Tsutsumi
authors.affiliation: Inserm, U836, Physiopathologie du cytosquelette, BP170, Grenoble, France; University Grenoble Alpes, Grenoble Institut des Neurosciences, BP170, Grenoble, France; Commissariat à l'énergie atomique, Institut de Recherches en Technologies et Sciences pour le Vivant, Groupe Physiopathologie du Cytosquelette, Grenoble, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Denarier
authors.affiliation: Division of Membrane Physiology, Department of Cell Physiology, National Institute for Physiological Sciences, Aichi, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Fukata
authors.affiliation: Inserm, U836, Physiopathologie du cytosquelette, BP170, Grenoble, France; University Grenoble Alpes, Grenoble Institut des Neurosciences, BP170, Grenoble, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Bosc
authors.affiliation: Inserm, U836, Physiopathologie du cytosquelette, BP170, Grenoble, France; University Grenoble Alpes, Grenoble Institut des Neurosciences, BP170, Grenoble, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Delaroche
authors.affiliation: Inserm, U836, Physiopathologie du cytosquelette, BP170, Grenoble, France; University Grenoble Alpes, Grenoble Institut des Neurosciences, BP170, Grenoble, France.
authors.forename: Nora
authors.initials: N
authors.lastname: Collomb
authors.affiliation: Division of Membrane Physiology, Department of Cell Physiology, National Institute for Physiological Sciences, Aichi, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Fukata
authors.affiliation: Department of Cell Biology, University of Geneva, Sciences III, Geneva, Switzerland.
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Martinou
authors.affiliation: Inserm, U836, Physiopathologie du cytosquelette, BP170, Grenoble, France; University Grenoble Alpes, Grenoble Institut des Neurosciences, BP170, Grenoble, France.
authors.forename: Karin
authors.initials: K
authors.lastname: Pernet-Gallay
authors.affiliation: Inserm, U836, Physiopathologie du cytosquelette, BP170, Grenoble, France; University Grenoble Alpes, Grenoble Institut des Neurosciences, BP170, Grenoble, France; Commissariat à l'énergie atomique, Institut de Recherches en Technologies et Sciences pour le Vivant, Groupe Physiopathologie du Cytosquelette, Grenoble, France.
authors.forename: Annie
authors.initials: A
authors.lastname: Andrieux
mesh_terms: D016475:3T3 Cells; D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D006056:Golgi Apparatus / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D011485:Protein Binding; D055503:Protein Multimerization; D021381:Protein Transport
chemical_list: C491894:MAP6 protein, human; D008869:Microtubule-Associated Proteins