9316206 Ballester The goal of this project is to characterize the function of three newly identified genes that inhibit the RAS-cAMP pathway in yeast. Determination of their mechanism of action will help advance our understanding of RAS action and the events involved in normal cell growth. Preliminary evidence discussed in a later section suggest that these genes play important roles in yeast. ESP18 encodes a serine and threonine rich protein and is an essential gene that inhibits the function of RAS. It is particularly interesting because it may encode a new class of proteins that are able to regulate Ras activity. IKS4 encodes a putative serine and threonine protein kinase that opposes the function of the cAMP- dependent protein kinase and it is a candidate for a growth inhibitor in yeast. SCP7 encodes another serine and threonine rich protein that inhibits the function of adenylate cyclase and may be part of a complex that includes adenylate cyclase and the associated protein, Cap. The specific aims of this research are: (1) To determine the function of the ESP18 gene: We will determine the function of the ESP18 gene by identifying other molecules that interact directly or are within the same pathway as ESP18. This will be accomplished by the isolation and characterization of extragenic mutants of an ESP18 temperature sensitive mutant. (2) To characterize the function of the IKS4 gene: We will characterize the function of the IKS4 gene by performing genetic analysis to determine its relation to other protein kinases that affect the RAS-cAMP pathway in yeast. (3) To better define the role of the SCP7 gene in the function of adenylate cyclase by performing genetic analysis to determine its relation to adenylate cyclase and the associated protein, Cap. We will also determine if the product of the SCP7 gene associates with adenylate cyclase or Cap by co- immunoprecipitiation of epitope tagged proteins. %%% The RAS genes of yeast are similar to cancer causing genes of animals. This research could provide insight into the origins of cancer. ***
