* To whom correspondence should be addressed.
Received February 19, 2012; Revision received March 12, 2012
The binding of both factors (eRF1 and eRF3) is essential for fast kinetics of the termination of protein translation. The C-terminal domain of eRF1 is known to interact with the C domain of eRF3. Eo-eRF1b contains two highly conserved tryptophan residues (W-11 and W-373), W-11 located in the Eo-eRF1b N domain and W-373 located in the Eo-eRF1b C domain. Fluorimetry was used to study the interactions of the proteins. When binding with Eo-eRF3Cm6, the emission peak of Eo-eRF1b is blue shifted, while the emission peak of Eo-eRF1bC has no notable change. Our results suggest that the eRF1–eRF3 interaction induces the N and C domain of eRF1b to become closer to each other.
KEY WORDS: steady-state fluorescence quenching, eRF1–eRF3 interaction, Euplotes octocarinatus