Intrinsic ATPase activity of yeast peptide chain elongation factor 3(EF-3) and its direct interaction with various nucleotides.

Whereas the ribosome-dependent ATPase activity of EF-3 required highly active ribosomes for its full activity, a catalytic site for ATP hydrolysis may reside in the EF-3 as being supported by the activity-EF-3/ribosome amount profiles. The direct interaction of EF-3 with various nucleotides such as GTP, UTP, CTP, dATP, ADP and AMPPNP as well as ATP was analyzed by protection experiments against trypsin digestion of the factor according to SDS-gel electrophoresis. The protection effect varied with the used nucleotides roughly in accordance with the inhibitory effect of those on the ribosome-dependent ATPase. The ATPase activity of EF-3 alone in the absence of ribosome was observed by using large amounts of the factor and the rate was two orders of magnitude lower than that of the ribosome-dependent.