The Isolation and Characterization of Elongation Factor eEF‐Ts from Krebs‐II Mouse‐Ascites‐Tumor Cells and Its Role in the Elongation Process

Abstract

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 25 500 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.

Functional and structural studies on a tryptic fragment of eucaryotic elongation factor Tu from rabbit reticulocytes

“…Purified eEF-Tu4 retains the ability to bind GTP (Figure 3) although this binding has been reduced to about 20% of that of the native enzyme. The native enzyme bound 0.073 pmol of GTP/pmol, a value in agreement with most (Legocki et al, 1974;Slobin & Moller, 1976;Grasmuk et al, 1978) but not all (Nagata et al, 1976) studies on figure 3: Binding of [3H]GTP by eEF-Tu (•) and eEF-Tu4 (O).…”

Affinity labeling of eukaryotic elongation factors using Nε-bromoacetyl-Lys-tRNA

“…In an effort to improve the aminoacyl bond protection and the efficiency of crosslinking to the eukaryotic factors, we surveyed a range of incubation conditions which included those found optimal by various groups (e.g., 6,12,28). But the protection and crosslinking were either reduced or not significantly changed when the following changes were made in the standard protocol: 2Mg + at 1, 3, or 10 mM; ([NH4 K + J) at 15, 43, 93, 100 or 143 mM; pH at, 7.6, 7.8, or 8.0; IGTP] at 0.1 mM; addition of glycerol to 25%; or addition of bovine serum albumin to 0.5 mg/ml.…”