| Abstract: | ATPase and GTPase activities of EF-3 were similarly inhibited by various nucleotides including CTP, UTP and four dNTP's. The low specificity of EF-3 was in remarkable contrast with the high specificity of EF-1 alpha and EF-2 directed only to quanine nucleotides. The pH-activity and salt concentration-activity profiles as well as the above inhibition experiments coincidently supported that the same active site functions for ATPase and GTPase of EF-3. The stimulation of poly(Phe) synthesis was not observed with AMPPNP in place of ATP. The stimulation required ATP hydrolysis, probably catalyzed by ATPase of EF-3. Reflecting the low specificity of the ATPase, UTP, dTTP, dATP and dGTP stimulated the poly(Phe) synthesis. EF-3 appears to drive yeast elongation cycle using the energy from ATP hydrolysis by its ATPase without serving for GTP regeneration. |
