Identification of the In Vivo Phosphorylation Sites of the Ras Suppressor Rsu-1
Uniformed Services University Of The Health Sciences Bethesda United States
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The Ras Suppressor Rsu-J is a 33 kDa protein originally discovered as a cDNA that suppressed v-Ras transformation of NIH-3T3 fibroblasts. Rsu-1 overexpression in several cell lines NIH-3T3, U251 , PC12, MCFl increased ERK activity and levels of p21sup CIP, and inhibited growth rate and decreased JNK activity. Stabilization of p53 and inhibition of CDK2 and cyclin D-associated kinase activity has also been observed in MCF7 cells stably transfected with Rsu-1. In this study we attempted to identify the binding proteins to Rsu-1 by the Far Western Cloning method. Preliminary experiments with a fusion protein containing the glutathione-S-transferaseGST tag and the carboxy-terminus of Rsu-1 showed binding to a protein of approximately 30 kDa both in solution and immobilized on nitrocellulose.