The isolation and characterization of elongation factor eEF-Ts from Krebs-II mouse-ascites-tumor cells and its role in the elongation process.

A factor having activity similar to that described in other systems for the eukaryotic elongation factor eEF-Ts was isolated from the heavy, aggregate form of eEF-TH (formally named EF-1H). This protein has a molecular weight of 52000 under native conditions and of 25500 under denaturing conditions. It has been shown to stimulate eEF-Tu-dependent aminoacyl-tRNA binding to ribosomes and therefore eEF-Tu/eEF-G-dependent polyphenylalanine synthesis by ribosomes and was found to stimulate GDP-GTP exchange in eEF-Tu . GDP complexes. In the course of this work, it was also demonstrated that the removal of deacylated tRNA from the ribosome is a GTP-dependent process. This report, therefore, adds further support to the concept that a third elongation factor, eEF-Ts, may be common to all systems in the eukaryotic domain.