title: Targeting the motor regulator Klar to lipid droplets.
abstract: BACKGROUND
  In Drosophila, the transport regulator Klar displays tissue-specific localization: In photoreceptors, it is abundant on the nuclear envelope; in early embryos, it is absent from nuclei, but instead present on lipid droplets. Differential targeting of Klar appears to be due to isoform variation. Droplet targeting, in particular, has been suggested to occur via a variant C-terminal region, the LD domain. Although the LD domain is necessary and sufficient for droplet targeting in cultured cells, lack of specific reagents had made it previously impossible to analyze its role in vivo.
  
  
  RESULTS
  Here we describe a new mutant allele of klar with a lesion specifically in the LD domain; this lesion abolishes both droplet localization of Klar and the ability of Klar to regulate droplet motion. It does not disrupt Klar's function for nuclear migration in photoreceptors. Using a GFP-LD fusion, we show that the LD domain is not only necessary but also sufficient for droplet targeting in vivo; it mediates droplet targeting in embryos, in ovaries, and in a number of somatic tissues.
  
  
  CONCLUSIONS
  Our analysis demonstrates that droplet targeting of Klar occurs via a cis-acting sequence and generates a new tool for monitoring lipid droplets in living tissues of Drosophila.
authors.affiliation: Department of Biology, University of Rochester, Rochester, NY 14627, USA.
authors.forename: Yanxun V
authors.initials: YV
authors.lastname: Yu
authors.forename: Zhihuan
authors.initials: Z
authors.lastname: Li
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Rizzo
authors.forename: Jenifer
authors.initials: J
authors.lastname: Einstein
authors.forename: Michael A
authors.initials: MA
authors.lastname: Welte
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D004330:Drosophila / Q000166:cytology / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism*; D050356:Lipid Metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure; D020409:Molecular Motor Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009685:Nuclear Envelope / Q000378:metabolism / Q000648:ultrastructure; D010053:Ovary / Q000378:metabolism / Q000648:ultrastructure; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism / Q000648:ultrastructure; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000235:genetics*; D016415:Sequence Alignment
chemical_list: D029721:Drosophila Proteins; D026901:Membrane Transport Proteins; D020409:Molecular Motor Proteins; D020033:Protein Isoforms; C401521:klar protein, Drosophila; D049452:Green Fluorescent Proteins