title: The 21.5-kDa isoform of myelin basic protein has a non-traditional PY-nuclear-localization signal.
abstract: The predominant 18.5-kDa classic myelin basic protein (MBP) is mainly responsible for compaction of the myelin sheath in the central nervous system, but is multifunctional, having numerous interactions with Ca(2+)-calmodulin, actin, tubulin, and SH3-domains, and can tether these proteins to a lipid membrane in vitro. The full-length 21.5-kDa MBP isoform has an additional 26 residues encoded by exon-II of the classic gene, which causes it to be trafficked to the nucleus of oligodendrocytes (OLGs). We have performed site-directed mutagenesis of selected residues within this segment in red fluorescent protein (RFP)-tagged constructs, which were then transfected into the immortalized N19-OLG cell line to view protein localization using epifluorescence microscopy. We found that 21.5-kDa MBP contains two non-traditional PY-nuclear-localization signals, and that arginine and lysine residues within these motifs were involved in subcellular trafficking of this protein to the nucleus, where it may have functional roles during myelinogenesis.
authors.affiliation: Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Graham S T
authors.initials: GS
authors.lastname: Smith
authors.forename: Lauren V
authors.initials: LV
authors.lastname: Seymour
authors.forename: Joan M
authors.initials: JM
authors.lastname: Boggs
authors.forename: George
authors.initials: G
authors.lastname: Harauz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D005091:Exons; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D004676:Myelin Basic Protein / Q000235:genetics / Q000378:metabolism*; D019913:Nuclear Localization Signals / Q000235:genetics / Q000378:metabolism*; D009836:Oligodendroglia / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism
chemical_list: C499047:Mbp protein, mouse; D004676:Myelin Basic Protein; D019913:Nuclear Localization Signals; D020033:Protein Isoforms