N‐terminal residues of the yeast pheromone receptor,Ste2p,mediate mating events independently of G1‐arrest signaling |
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Authors: | Chunhua Shi Stephanie C. Kendall Eric Grote Susan Kaminskyj Michèle C. Loewen |
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Affiliation: | 1. Plant Biotechnology Institute, National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK, Canada S7N 0W9;2. Department of Biochemistry, 107 Wiggins Road, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E2;3. Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Baltimore, Maryland 21205;4. Department of Biology, 112 Science Place, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E5 |
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Abstract: | In Saccharomyces cerevisiae, mechanisms modulating the mating steps following cell cycle arrest are not well characterized. However, the N‐terminal domain of Ste2p, a G protein‐coupled pheromone receptor, was recently proposed to mediate events at this level. Toward deciphering receptor mechanisms associated with this mating functionality, scanning mutagenesis of targeted regions of the N‐terminal domain has been completed. Characterization of ste2 yeast overexpressing Ste2p variants indicated that residues Ile 24 and Ile 29 as well as Pro 15 are critical in mediating mating efficiency. This activity was shown to be independent of Ste2p mediated G1 arrest signaling. Further analysis of Ile 24 and Ile 29 highlight the residues' solvent accessibility, as well as the importance of the hydrophobic nature of the sites, and in the case of Ile 24 the specific size and shape of the side chain. Mutation of these Ile's led to arrest of mating after cell contact, but before completion of cell wall degradation. We speculate that these extracellular residues mediate novel receptor interactions with ligand or proteins, leading to stimulation of alternate signaling effector pathways. J. Cell. Biochem. 107: 630–638, 2009. © 2009 Crown in the right of Canada. |
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Keywords: | G protein‐coupled receptor mating mutagenesis Ste2p yeast |
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