Protein synthesis in rabbit reticulocytes: Characteristics of a ribosomal factor that reverses inhibition of protein synthesis in heme-deficient lysates

A ribosomal salt (0.5 M KCI) wash factor (RF) that reverses inhibition of protein synthesis in heme-deficient reticulocyte lysates has been resolved from the bulk of Met-tRNAtmet- binding factor (EIF-1), Co-EIF-I, and EIF-2 (ternary complex dissociation factor, TDF). The purified RF restores protein synthesis activity of heme-deficient lysates to the level observed in the presence of hemin. No direct correlation exists between amount of EIF-i activity and ability to reverse inhibition of protein synthesis in heme-deficient lysates. Homogeneous preparations of EIF-i are completely inactive in reversal of protein synthesis inhibition in heme-deficient lysates. These findings suggest that RF activity is not due to EIF-i alone but may or may not require EIF-i as a component of a complex factor