QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Choi, K.-Y. Articles by Elion, E. A. Search for Related Content PubMed PubMed Citation Articles by Choi, K.-Y. Articles by Elion, E. A.

Vol. 10, Issue 5, 1553-1568, May 1999

Characterization of Fus3 Localization: Active Fus3 Localizes in Complexes of Varying Size and Specific Activity

Kang-Yell Choi,^* Janice E. Kranz,^* Sanjoy K. Mahanty,^* Ki-Sook Park, and Elaine A. Elion^*§

 ^*Department of Biological Chemistry and Molecular Pharmacology Harvard Medical School, Boston, Massachusetts 02115-5701; and  Department of Biochemistry and Molecular Biology, Institute of Genetic Science, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-Gu, Seoul, Korea

The MAP kinase Fus3 regulates many different signal transduction outputs that govern the ability of Saccharomyces cerevisiae haploid cells to mate. Here we characterize Fus3 localization and association with other proteins. By indirect immunofluorescence, Fus3 localizes in punctate spots throughout the cytoplasm and nucleus, with slightly enhanced nuclear localization after pheromone stimulation. This broad distribution is consistent with the critical role Fus3 plays in mating and contrasts that of Kss1, which concentrates in the nucleus and is not required for mating. The majority of Fus3 is soluble and not bound to any one protein; however, a fraction is stably bound to two proteins of ~60 and ~70 kDa. Based on fractionation and gradient density centrifugation properties, Fus3 exists in a number of complexes, with its activity critically dependent upon association with other proteins. In the presence of  factor, nearly all of the active Fus3 localizes in complexes of varying size and specific activity, whereas monomeric Fus3 has little activity. Fus3 has highest specific activity within a 350- to 500-kDa complex previously shown to contain Ste5, Ste11, and Ste7. Ste5 is required for Fus3 to exist in this complex. Upon  factor withdrawal, a pool of Fus3 retains activity for more than one cell cycle. Collectively, these results support Ste5's role as a tether and suggest that association of Fus3 in complexes in the presence of pheromone may prevent inactivation in addition to enhancing activation.

---

   Present address: Department of Biochemistry, Brandeis University, Waltham, MA 02454-9110.
^§   Corresponding Author: Elaine A. Elion. E-mail address: elion{at}bcmp.med.harvard.edu.

---

Molecular Biology of the Cell
Vol. 10, 1553-1568, May 1999
Copyright © 1999 by The American Society for Cell Biology

This article has been cited by other articles:

				E. M. Rubenstein and M. C. Schmidt Mechanisms Regulating the Protein Kinases of Saccharomyces cerevisiae Eukaryot. Cell, April 1, 2007; 6(4): 571 - 583. [Full Text] [PDF]

				D. Shao, W. Zheng, W. Qiu, Q. Ouyang, and C. Tang Dynamic Studies of Scaffold-Dependent Mating Pathway in Yeast Biophys. J., December 1, 2006; 91(11): 3986 - 4001. [Abstract] [Full Text] [PDF]

				K. S. Bruno, F. Tenjo, L. Li, J. E. Hamer, and J.-R. Xu Cellular Localization and Role of Kinase Activity of PMK1 in Magnaporthe grisea Eukaryot. Cell, December 1, 2004; 3(6): 1525 - 1532. [Abstract] [Full Text] [PDF]

				Y. Wang and E. A. Elion Nuclear Export and Plasma Membrane Recruitment of the Ste5 Scaffold Are Coordinated with Oligomerization and Association with Signal Transduction Components Mol. Biol. Cell, June 1, 2003; 14(6): 2543 - 2558. [Abstract] [Full Text] [PDF]

				E. Blackwell, I. M. Halatek, H.-J. N. Kim, A. T. Ellicott, A. A. Obukhov, and D. E. Stone Effect of the Pheromone-Responsive G{alpha} and Phosphatase Proteins of Saccharomyces cerevisiae on the Subcellular Localization of the Fus3 Mitogen-Activated Protein Kinase Mol. Cell. Biol., February 15, 2003; 23(4): 1135 - 1150. [Abstract] [Full Text] [PDF]

				M. V. Metodiev, D. Matheos, M. D. Rose, and D. E. Stone Regulation of MAPK Function by Direct Interaction with the Mating-Specific Galpha in Yeast Science, May 24, 2002; 296(5572): 1483 - 1486. [Abstract] [Full Text] [PDF]

				E. A. Elion The Ste5p scaffold J. Cell Sci., March 13, 2002; 114(22): 3967 - 3978. [Abstract] [Full Text] [PDF]

				G. Pearson, F. Robinson, T. Beers Gibson, B.-e Xu, M. Karandikar, K. Berman, and M. H. Cobb Mitogen-Activated Protein (MAP) Kinase Pathways: Regulation and Physiological Functions Endocr. Rev., April 1, 2001; 22(2): 153 - 183. [Abstract] [Full Text]