Dietary calorie restriction does not affect the levels of protein elongation factors in rat livers during ageing

Dietary calorie restriction of rats has been previously shown to increase protein synthetic rates in liver and kidney cells during ageing. Here we have compared the activiy and amounts of active elongation factors EF-1α and EF-2 in cell-free extracts prepared from livers isolated from male Fischer 344 rats of different ages. Although there is some age-related decline in the catalytic activity and amounts of active EF-1α during ageing, no differences between freely-fed and calorie-restricted animals were observed. In the case of EF-2, the amounts of ADP-ribosylatable EF-2 neither declined during ageing nor differed between freely-fed and calorie-restricted animals. Thus differences in the protein synthetic rates in calorie-restricted and freely-fed rats are not reflected at the level of protein elongation factors, and may involve some other mechanisms of regulation.