Construction of His-tagged ATR Fusion Proteins: Working toward the Identification of ATR-interacting Proteins
The protein kinase A TR is responsible for initiating signal transmission at cell cycle checkpoints. A TR is a 303 kDa protein containing a carboxy-terminus kinase domain related to PI-3 kinase, and is homologous to the ATM gene product in human cells and the rad3lMECl proteins in yeast. These proteins, together with DNA-PK, are part of the family of PI-3 kinase-related kinases (PIKKs). All members of this family play important roles in cell cycle checkpoints and operate to permit cell survival following many forms of DNA damage. Upon damage of DNA in eukaryotic cells, ATR undergoes a dramatic intranuclear relocalization, translocating to nuclear foci that represent sites of DNA damage and repair. The ultimate goals of this research are to identify new checkpoint pathway substrates that A TR is able to phosphorylate post-DNA damage, and to initiate the identification of potential inhibitors of A TR function. This study commenced by dividing A TR into seven fragments. These fragments were subsequently cloned into a vector system and transformed in order to generate A TR fusion proteins. The induction of these fusion constructs, mediated by their screening and conditioning, is subject to a wide variety of specifications. Because the optimal induction conditions have yet to be discovered, fine-tuning of the experimental techniques must continue in order to give this research a higher degree of significance. However, once successfully induced, a series of co-transfection experiments may be initiated, in which the activity of A TR, plus several additional proteins can be monitored under condition of DNA damage.
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