Analysis of the Fission Yeast Rad3+ Gene Product

摘要

The fission yeast Rad3 protein is representative of a class of proteins that play a crucial role in genome maintenance in all eukaryotic cell. In cells lacking Rad3, normal cell cycle arrest and DNA repair are not induced in response to damage. As a result, such cells are extremely sensitive to DNA damage or inhibition of DNA replication. The related human protein, Atm, is responsible for the severe congenital disorder Ataxia Telengiectasia, which is associated with radiation sensitivity and greatly elevated cancer risk. Related proteins have been found in many other eukaryotes including budding yeast, flies, frogs and mice, where they also play a crucial role in the response to DNA damage. All of these proteins are large (>2OOkD) protein kinases with a conserved kinase motif in the C-terminus. Although the kinase motif mostly closely resembles phosphoinositol-3 kinases, it is only known to phosphorylate proteins. Our working model is that damage selectively activates the Rad3 kinase, which then phosphorylates substrates involved in cell cycle control and repair of DNA damage. The goal of this project was to identify Rad3 Interacting proteins in order to learn how Rad3 is activated and what its substrates are.