ASH1 mRNA localization in three acts.
Novel green fluorescent protein (GFP) labeling techniques targeting specific mRNA transcripts reveal discrete phases of mRNA localization in yeast: packaging, transport, and docking. In budding yeast, ASH1 mRNA is translocated via actin and myosin to the tip of growing cells. A GFP-decorated reporter transcript containing the ASH1 3' untranslated region gRNA(ASH1) forms spots of fluorescence localized to a cortical domain at the bud tip, relocates to the mother-bud neck before cell separation, and finally migrates to the incipient bud site before the next budding cycle. The correct positioning of the mRNA requires at least six proteins: She1p-5p and Bud6p/Aip3p. gRNA(ASH1) localization in mutant strains identified three functional categories for the She proteins: mRNA particle formation (She2p and She4p), mRNA transport into the bud (She1p/Myo4p and She3p), and mRNA tethering at the bud tip (She5p/Bni1p and Bud6p/Aip3p). Because localization of the mRNA within the bud does not a priori restrict the translated protein, we examine the distribution of a mother-specific protein (Yta6p) translated from a mRNA directed into the bud. Yta6p remains associated with the mother cortex despite localization of the mRNA to the bud. This video essay traces the life history of a localized mRNA transcript, describes the roles of proteins required to polarize and anchor the mRNA, and demonstrates at least one instance where mRNA localization does not effect protein localization.
Beach
D L
DL
Department of Biology, University of North Carolina, Chapel Hill, NC 27599-3280, USA. dbeach@email.unc.edu
Bloom
K
K
D001692:Biological Transport; D002455:Cell Division; D016764:Cell Polarity; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000235:genetics; D005800:Genes, Fungal / Q000235:genetics*; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D020409:Molecular Motor Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics*; D058727:RNA, Small Untranslated
C098733:ASH1 protein, S cerevisiae; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D008164:Luminescent Proteins; D020409:Molecular Motor Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; C111369:SHE4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D058727:RNA, Small Untranslated