Creatine Synthesis from the Amino Acids

Creatine Synthesis from the Amino Acids,
Arginine, Glycine and Methionine

Legend: Reaction 1 (catalyzed by AGAT) is the rate limiting step in creatine biosynthesis. AGAT expression is also reduced by the presence of creatine. This raised concerns that prolonged creatine supplementation might inhibit endogenous creatine synthesis for an indefinite period of time.

Finally, notice that Glycine is completely incorporated into the creatine backbone, whereas Arginine and Methionine only contribute side groups.