 The elongation phase of translation is promoted by three universal elongation factors, EF-Tu, EF-Ts, and EF-G. EF-P was discoverd in 1975 by Glick and Ganoza, as a factor that increased the yield of peptide bond formation between initiator fMet-tRNAfMet and a mimic of aa-tRNA, puromycin (Pmn).The low yield of product formation in absence of EF-P can be described by the loss of peptidyl-tRNA from the stalled ribosome.Thus, EF-P is not a necessary component of minimal in vitro of translation system, however, the absence of EF-P can limit translation rate, increase antibiotic sensitivity, and slow growth.