Oteins GS and GOGAT, as well as the activity of GS, can be regulated in multiple ways (6?). On the other hand, for many other carbon and energy sources used for growth of E. coli, the ATP requirement of ammonium assimilation through GS-GOGAT as a percentage of the total ATP turnover is smaller than that for glucose, suggesting that the extra ATP requirement of the GS-GOGAT pathway would be tolerab