A New Concept of the Function of Elongation Factor 1 in Peptide Chain Elongation

Abstract

An entirely new model for the mechanism of elongation factor 1 (EF-1) function is presented. Experiments, in which mixtures of rH]EF-1, ribosomes from Krebs I1 ascites cells and various additional co-factors were analyzed by chromatography on Sepharose 6B, show that EF-1 binds to the ribosome early in the translation process and remains bound on the ribosome during translation. Optimal EF-1 binding occurs on polynucleotide-programmed ribosomes carrying a tRNA in their P-site.On the other hand it was clearly shown that EF-2 attached at each translocation event and was then released before a new Phe-tRNA could be bound.

Further Evidence that Elongation Factor 1 Remains Bound to Ribosomes during Peptide Chain Elongation

“…Pure, functionally active, preparations of the monomer form of EF-1 have recently become available from a number of tissues [30,11]. These preparations have made it possible to state definitely that one molecule of enzyme stimulates the attachment of only one aminoacyl-tRNA molecule to the decoding site of an mRNA-programmed eukaryotic ribosome [I 11.…”

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

“…The sources of some of the reagents used were as stated previously [8]. DEAE-Sephadex A-50 came from Pharmacia Fine Chemicals (Uppsala, Sweden) and Ultrogel AcA 44 from LKB Instruments (Stockholm, Sweden).…”

Interchangeability of elongation factor‐Tu and elongation factor‐1 in aminoacyl‐tRNA binding to 70 S and 80 S ribosomes

“…The reagents used in this study came from the same sources as stated previously [2] . The preparation of Escherichia coli elongation factors followed instructions given by Arai et al [3] .…”

“…E. coli ribosomes were prepared and washed fourtimes with 0.5 M NH4Cl as described previously [S] . Washed ribosomes and aggregated and monomeric forms of EF-1 in the labeled and unlabeled form from ascites tumor cells were prepared as published elsewhere [2] . Similarly, the charging of crude, unfractionated E. coli t RNA with [ i4C] phenylalanine (1160 dpm/pmol) followed published procedures [6] …”

“…The filters were dried, introduced into plastic vials containing 5 ml butyl-PBD (Ciba) and counted in a Packard liquid scintillation counter, model 3385. Gel electrophoresis of the purified elongation factors followed published procedures [2] .…”