| Abstract: | The two E. coli supernatant proteins which were previously designated as factors A and B, and which were shown to activate ribosomes for initiation, are very probably factors EF-Ts and EF-G, respectively. An EF-Ts preparation, homogeneous when analyzed by polyacrylamide gel electrophoresis, contained considerable A activity. The EF-Ts and A activities differed, however, in their heat sensitivity and in the amount of the preparation required. An electrophoretically-homogeneous preparation of EF-G retained strong B activity. The amount of the preparation required for EF-G and B activity and the heat sensitivity of the two activities were similar. GTP enhanced the activation of the ribosomes by factors A and B. |
