Repression of an Acetylornithine Permeation System

plete mixture of amino acids resulted in a large suppression of the incorporation.The reason for this effect is also unknown.It may be caused by an imbalance of amino acids since, in a cell-free preparation from E. coli, a balanced mixture of amino acids that reflect the composition of E. coli protein is superior to an equi- molar mixture of amino acids.Summary.-A system from developing maize endosperm consisting of washed particles plus a pH 5.2 fraction from the supernatant that actively incorporates leucine-C4 -into protein is described.The system requires a source of energy and GTP.The incorporation is inhibited by treatment with ribonuclease or chloramphenicol.When operating optimally, the incorparation-efficiency is 1 to 2 per cent of the added isotope making this system comparable to the mammalian systems.