A cycloheximide sensitivity factor from yeast required for N-acetylphenylalanylpuromycin formation

Abstract

A protein (factor P) was isolated from yeast, which was required for sensitivity to cycloheximide of a partially purified polyphenylalanine synthesis system. In the absence of factor P, 10-3 M cycloheximide was required for 50% inhibition of polyphenylalanine synthesis, while, in its presence, 10-6 M gave 50% inhibition. Coincident with cycloheximide sensitivity was an activity required for EF-2 dependent N-acetylphenylalanylpuromycin (N-AcPhePuro) formation. Transfer of N-AcPhe to puromycin from the tRNA bound in the presence of 26 mM MgCl2 required factor P, as well as EF-2. Studies with [rabbit] antibody against EF-2 demonstrated that P factor was not required during the EF-2 translocation step but for some subsequent step.