Eucaryotic Elongation Factors Ts Is an Integral Component of Rabbit Reticulocyte Elongation Factor 1

Abstract

Elongation factor 1 (EF-1) purified from rabbit reticulocytes contained at least 2 distinct polypeptides, one of MW 53,000 and one of MW 30,000. The 30,000-MW polypeptide was purified from EF-1 by treatment of the factor with 5.4 M guanidine.cntdot.HCl and subsequent chromatography on DEAE-BioGel A in the presence of 5 M urea. A number of functional criteria showed that the 30,000-MW polypeptide was the eukaryotic elongation factor Ts (eEF-Ts). These criteria include the ability of the polypeptide to stimulate Artemia salina eEF-Tu-dependent binding of aminoacyl-tRNA to 80-S ribosomes and eEF-Tu + EF-2-dependent polyphenylalanine synthesis. The reticulocyte factor markedly increased the rate of exchange of eEF-Tu.cntdot.GDP complexes with free GTP. Rabbit antibodies to EF-1 from A. salina, previously shown to contain eEF-Ts, cross-reacted with reticulocyte eEF-Ts, suggesting extensive structural homology between brine shrimp and rabbit eEF-Ts. The eEF-Ts is an integral component of EF-1 from such diverse sources as brine shrimp and rabbit reticulocytes; the factor is apparently universally present in eukaryotic EF-1.