title: Isolation of a ribonucleoprotein complex involved in mRNA localization in Drosophila oocytes.
abstract: Localization of bicoid (bcd) mRNA to the anterior and oskar (osk) mRNA to the posterior of the Drosophila oocyte is critical for embryonic patterning. Previous genetic studies implicated exuperantia (exu) in bcd mRNA localization, but its role in this process is not understood. We have biochemically isolated Exu and show that it is part of a large RNase-sensitive complex that contains at least seven other proteins. One of these proteins was identified as the cold shock domain RNA-binding protein Ypsilon Schachtel (Yps), which we show binds directly to Exu and colocalizes with Exu in both the oocyte and nurse cells of the Drosophila egg chamber. Surprisingly, the Exu-Yps complex contains osk mRNA. This biochemical result led us to reexamine the role of Exu in the localization of osk mRNA. We discovered that exu-null mutants are defective in osk mRNA localization in both nurse cells and the oocyte. Furthermore, both Exu/Yps particles and osk mRNA follow a similar temporal pattern of localization in which they transiently accumulate at the oocyte anterior and subsequently localize to the posterior pole. We propose that Exu is a core component of a large protein complex involved in localizing mRNAs both within nurse cells and the developing oocyte.
authors.affiliation: Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, California 94143, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Wilhelm
authors.forename: J
authors.initials: J
authors.lastname: Mansfield
authors.forename: N
authors.initials: N
authors.lastname: Hom-Booher
authors.forename: S
authors.initials: S
authors.lastname: Wang
authors.forename: C W
authors.initials: CW
authors.lastname: Turck
authors.forename: T
authors.initials: T
authors.lastname: Hazelrigg
authors.forename: R D
authors.initials: RD
authors.lastname: Vale
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism; D004527:Egg Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D005260:Female; D006801:Humans; D019476:Insect Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009865:Oocytes / Q000378:metabolism; D009866:Oogenesis; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012259:Ribonuclease, Pancreatic / Q000378:metabolism; D012261:Ribonucleoproteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D004527:Egg Proteins; D019476:Insect Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; C109692:YPS protein, Drosophila; C072067:exu protein, Drosophila; C091675:osk protein, Drosophila; D012259:Ribonuclease, Pancreatic