The evaluation of anoxia responsive E2F DNA binding activity in the red eared slider turtle， .

In many cases， the DNA-binding activity of a transcription factor does not change， while its transcriptional activity is greatly influenced by the make-up of bound proteins. In this study， we assessed the protein composition and DNA-binding ability of the E2F transcription factor complex to provide insight into cell cycle control in an anoxia tolerant turtle through the use of a modified ELISA protocol. This modification also permits the use of custom DNA probes that are tailored to a specific DNA binding region， introducing the ability to design capture probes for non-model organisms. Through the use of EMSA and ELISA DNA binding assays， we have successfully determined the DNA binding activity and complex dynamics of the Rb/E2F cell cycle regulatory mechanisms in an anoxic turtle， . Repressive cell cycle proteins (E2F4， Rb， HDAC4 and Suv39H1) were found to significantly increase at E2F DNA-binding sites upon anoxic exposure in anoxic turtle liver. The lack of p130 involvement in the E2F DNA-bound complex indicates that anoxic turtle liver may maintain G arrest for the duration of stress survival.