Cell Biology

Where to Mate

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Science  23 Jul 2010:
Vol. 329, Issue 5990, pp. 371
DOI: 10.1126/science.329.5990.371-c

When yeast cells detect mating pheromone, they undergo polarized growth or “shmoo” formation at the end of the cell facing the highest concentration of pheromone. Garrenton et al. report that this polarization relies on a localized accumulation of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] and consequent activation of the mitogen-activated protein kinase (MAPK) Fus3. The authors monitored the abundance and localization of PtdIns(4,5)P2 in pheromone-treated cells with fluorescent probes that contained the pleckstrin homology (PH) domain, which binds with high affinity and specificity to PtdIns(4,5)P2. The probe accumulated at the shmoo tip and was not seen in cells lacking the kinase that mediates the synthesis of PtdIns(4,5)P2. The MAPK scaffold protein Ste5 contains a PH domain that binds PtdIns(4,5)P2, and Ste5 was localized to the shmoo tip as long as PtdIns(4,5)P2 synthesis was sustained. The Ste5 scaffold brings together the kinase Fus3 and its activating kinases, and activation of Fus3 in response to pheromone was lost when synthesis of PtdIns(4,5)P2 at the shmoo tip was blocked.

Proc. Natl. Acad. Sci. U.S.A. 107, 11805 (2010).

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