We are using biochemical, cell biological, genetic, and molecular approaches in conjunction with the yeast system to better understand the function of enzymes involved in the production of isoprenylated proteins. Examples of isoprenylated proteins include the Ras family of oncoproteins, Ras-related proteins, kinases, and secreted fungal mating pheromones, among many others. Understanding the function of these proteases may lead to novel therapeutic strategies for cancer, Alzheimer's disease, and other diseases.
The Farnesyl Transfersase: The farnesyl transferase (FTase) acts on proteins with a CaaX motif such that the Cysteine of the motif becomes covalently modified with the farnesyl lipid. The specificity of the FTase is being investigated using both in vivo and in vitro reporters. We are specifically testing whether the FTase has broader specificity than previously proposed.
The CaaX proteases: Rce1p and Ste24p are ER membrane-localized proteases. These proteases are essential for the maturation of isoprenylated molecules that are involved in a variety of cellular processes. Because Rce1p is specifically required for maturation of the oncoproteins Ras and RhoB, we are aiming to define the proteolytic mechanism of Rce1p and to develop pharmacological inhibitors that have anti-tumor potential. Rce1p has partial overlapping function with the ER membrane-localized, zinc-dependent Ste24p protease, which has been linked to premature aging (progeria) because of its role in the processing of lamin A. Thus, we are also trying to understand the functional differences of Rce1p and Ste24p to better understand their relative physiological importance.
The M16A proteases: These zinc-dependent enzymes are evolutionarily widespread from bacteria to humans. Examples include Ste23p and Axl1p, which mediate production of the yeast a-factor mating pheromone, and the insulin-degrading enzyme, which has a proposed protective function in Alzheimer's disease (AD). Our research on is designed is to gain a better understanding of these largely uncharacterized proteases, thus potentially providing novel insight into new methods for the treatment of AD.