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ASH1
mRNA localizes to the bud tip in Saccharomyces cerevisiae
to establish asymmetry of HO expression, important for mating type
switching. To visualize real time localization of the mRNA in living
yeast cells, green fluorescent protein (GFP) was fused to the RNA-binding
protein MS2 to follow a reporter mRNA containing MS2-binding sites.
Formation and localization of a GFP particle in the bud required
ASH1 3'UTR (untranslated region) sequences. The SHE
mutants disrupt RNA and particle localization and SHE 2 and
3 mutants inhibit particle formation as well. Both She3myc and She1myc
colocalized with the particle. Video microscopy demonstrated that
She1p/Myo4p moved particles to the bud tip at 200-440 nm/sec. Therefore,
the ASH1 3'UTR-dependent particle serves as a marker for
RNA transport and localization. |
