Figure 2.
Effect of isocaloric protein restriction on methyl transfer in the rat. Rats were placed on a casein based 6% protein diet for 7 to 10 days, controls were on a 24% protein diet and were pair fed. Dietary protein restriction resulted in a marked upregulation (red boxes) of 3-phosphoglycerate dehydrogenase (3PGDH), phosphoserineaminotransferase (PSAT), glutamate-cysteine ligase (GCL),and cysteinesulfinic acid decarboxylase (CSAD).The activity of cystathionine beta synthase (CβS) and cystathionine gamma lyase (CγL) was decreased ( blue boxes). Tracer dilution measured rate of appearance of serine and the rate of transmethylation of methionine ware increased (heavy arrows). Figure reproduced from Kalhan et al, Journal of Biological Chemistry 286:5266-5277,2011.