EUKARYOTIC ELONGATION FACTORS TS IS AN INTEGRAL COMPONENT OF RABBIT RETICULOCYTE ELONGATION FACTOR-1

Elongation factor 1 (EF‐1) was purified from rabbit reticulocytes and found to contain at least two distinct polypeptides: one of Mr 53000 and one of Mr 30000. The 30000‐Mr polypeptide was purified from EF‐1 by treatment of the factor with 5.4 M guanidine · HCl and subsequent chromatography on DEAE‐BioGel A in the presence of 5 M urea. By a number of functional criteria, the 30000‐Mr polypeptide was found to be the eucaryotic 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 as well as eEF‐Tu + EF‐2‐dependent polyphenylalanine synthesis. The reticulocyte factor also markedly increased the rate of exchange of eEF‐Tu · GDP complexes with free GTP. Furthermore, rabbit antibodies to EF‐1 from A. salina which was previously shown to contain eEF‐Ts [Slobin, L. I. and Möller, W. (1978) Eur. J. Biochem. 84, 69–77] were found to cross‐react with reticulocyte eEF‐Ts, suggesting extensive structural homology between brine shrimp and rabbit eEF‐Ts. The demonstration that eEF‐Ts is an integral component of EF‐1 from such diverse sources as brine shrimp and rabbit reticulocytes supports the conclusion that the factor is universally present in eucaryotic EF‐1. Copyright © 1979, Wiley Blackwell. All rights reserved