Abstract
Incorporation of L-leucine-C14 was studied in a cell free system consisting of the 10,000 x g liver supernatant, ATP and ATP generating system. Such a system prepared from livers of thyroidectomized animals kept on I free diet showed marked impairment in the incorporation of L-leucine-C14 into proteins. This impairment can be corrected by pretreatment of the animals with triiodothyronine (T3). But not with growth hormone. Addition of T3 in vitro had no effect.