MCB-9728218 Johnson, Douglas The long-term objective of this project is to understand the signal transduction mechanisms that control cell morphogenesis during the eukaryotic cell cycle. The goal of this study is to decipher the signaling pathways that control cell polarity in the yeast Saccharomyces cerevisiae. Polarized growth in response to normal or aberrant signals during the yeast cell cycle can result in several different morphological structures. We have previously characterized two proteins that are integral components of the cell polarity pathway in yeast: a Cdc42p GTPase and a Cdc24p, its guanine nucleotide exchange factor. The observation that both have counterparts in other eukaryotes suggests that common signal transduction mechanisms control cell polarity in different cell types. The specific aims of this study are to understand the molecular interactions of Cdc42p with its upstream regulators, including Cdc24p, and several downstream effectors. Also to be addressed is how the subcellular localization of these proteins is regulated. To study these interactions and their role in control of cell polarity, studies are proposed that combine several genetic, cell biological and biochemical approaches.
