Two steps: arginine hands its guanidino group to glycine, then SAM adds a methyl group
Route: Arginine + Glycine → Guanidinoacetate → Creatine
Glycine amidinotransferase moves the guanidino group of arginine onto the amino group of glycine. Ornithine is left over, and guanidinoacetate is made. Guanidinoacetate N-methyltransferase then takes a methyl group from SAM, which leaves as SAH, and the product is creatine. Muscle stores creatine as phosphocreatine, which passes its phosphoryl group to ADP to make ATP.
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| Step | Enzyme | EC | In | Out |
|---|---|---|---|---|
| 1 | Glycine amidinotransferase | 2.1.4.1 | Ornithine | |
| 2 | Guanidinoacetate N-methyltransferase | 2.1.1.2 | SAM | SAH |
Enzyme names and EC numbers are those used on the interactive board. Checked against sources: see the claim table in the repository (tools/pathway_data/checks).