Protein synthesis in 3T3 cells stimulated to proliferate at various rates

Reproducible conditions were defined for using rates of leucine incorporation as a valid measure of rates of de novo protein synthesis in mouse 3T3 cells. Upon stimulation of quiescent cultures, rates of de novo synthesis of proteins increased and pool levels of amino acids decreased in proportion to the concentration of serum in the stimulating medium. Rates of de novo protein synthesis (per cell) exhibited a biphasic pattern of increase. These rates approached a plateau value at the end of the lag phase and increased again as cells entered S phase. This pattern of behaviour helps to explain the observed relationships between cell growth (increase in mass) and cell proliferation (increase in cell number).