Why are gtp used in protein synthesis?
I can only guess...some probable reasons maybe :
1. many cellular processes require ATP, hence there are many ATP
binding proteins. Also, protein synthesis is a continuous process
in the cell with a majority of cell wt being constituted by
ribosomes. Hence, 2 different energy sources would mean less
competition between enzymes for ATP binding.
2. During nutritional stress, protein synthesis occurs at an
enhanced rate. Thus, there may be a functional need to de-couple
energy status of the cell (decreased ATP) with protein
biosynthesis. Although, I'm not sure if use of GTP is the cause or
effect of this phenomenon(!)