Medicine and Health Sciences Commons^™

The Gtp-Bound Form Of The Yeast Ran/Tc4 Homologue Blocks Nuclear Protein Import And Appearance Of Poly(A)+ Rna In The Cytoplasm., Gabriel Schlenstedt, Claudio Saavedra, Jonathan D. Loeb, Charles N. Cole, Pamela A. Silver

Dartmouth Scholarship

Ran/TC4, a Ras-like GTP-binding protein, and its nucleotide exchanger, RCC1, have been implicated in control of protein movement into the nucleus and cytoplasmic accumulation of mRNA. Saccharomyces cerevisiae contains two homologues of the mammalian Ran/TC4, encoded by the GSP1 and GSP2 genes. We have constructed yeast strains that overproduce either wild-type Gsp1 or a form of Gsp1 with glycine-21 converted to valine (Gsp1-G21V), which we show stabilizes the GTP-bound form. Cells producing Gsp1-G21V have defects in localization of nuclear proteins; nuclear proteins accumulate in the cytoplasm following galactose induction of Gsp1-G21V. Similarly, cells producing Gsp1-G21V retain poly(A)+ RNA in their …