Phosphorylation Regulates the Yeast Rab GTPase Sec4p
Author Information
Author(s): Christopher D. Heger, Christiane D. Wrann, Ruth N. Collins
Primary Institution: Cornell University
Hypothesis
Phosphorylation acts as a negative regulatory event for the yeast Rab GTPase Sec4p in regulating polarized growth.
Conclusion
Phosphorylation of Sec4p prevents its interaction with the effector Sec15p, inhibiting its function in exocytosis.
Supporting Evidence
- Phosphorylation of Sec4p inhibits its interaction with the exocyst component Sec15p.
- Mutations at phosphorylation sites showed that alanine substitutions retained function while phosphomimetic substitutions did not.
- Sec4p is essential for the delivery of post-Golgi vesicles to the plasma membrane.
Takeaway
This study shows that adding a phosphate group to a protein called Sec4p stops it from doing its job in helping cells grow and move things around.
Methodology
The study used yeast strains, Western blot analysis, fluorescence microscopy, yeast two-hybrid assays, and electron microscopy to investigate Sec4p phosphorylation.
Limitations
The study primarily focuses on a single Rab GTPase and its specific phosphorylation sites, which may not represent broader mechanisms in other proteins.
Digital Object Identifier (DOI)
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