ASH1 mRNA localization in three acts

Mol Biol Cell. 2001 Sep;12(9):2567-77. doi: 10.1091/mbc.12.9.2567.

Abstract

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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Biological Transport
  • Cell Division
  • Cell Polarity
  • Cytoplasm / genetics
  • Cytoplasm / metabolism
  • Cytoskeletal Proteins
  • DNA-Binding Proteins*
  • Fungal Proteins / genetics
  • Genes, Fungal / genetics*
  • Green Fluorescent Proteins
  • Luminescent Proteins / metabolism
  • Microscopy, Fluorescence
  • Microscopy, Video
  • Molecular Motor Proteins / genetics
  • Molecular Motor Proteins / metabolism
  • Mutation / genetics
  • Protein Transport
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism*
  • RNA, Small Untranslated
  • Repressor Proteins*
  • Saccharomyces cerevisiae / cytology*
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism
  • Transcription Factors / genetics*

Substances

  • ASH1 protein, S cerevisiae
  • Cytoskeletal Proteins
  • DNA-Binding Proteins
  • Fungal Proteins
  • Luminescent Proteins
  • Molecular Motor Proteins
  • RNA, Messenger
  • Repressor Proteins
  • SHE4 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • Green Fluorescent Proteins
  • RNA, Small Untranslated