GAMT Enzyme — Glossary | Creatine.my

Written by Creatine.my Editorial Team · · 3 min read
3 min read

What is GAMT?

GAMT (guanidinoacetate N-methyltransferase) is the enzyme that catalyzes the second and final step of endogenous creatine synthesis.

Located primarily in the liver, GAMT converts guanidinoacetate (GAA) into creatine by transferring a methyl group from S-adenosylmethionine (SAM).

This methylation reaction is metabolically significant: creatine synthesis consumes approximately 40% of all SAM-derived methyl groups in the body, making it the single largest consumer of methyl donors.

The Methylation Connection

The GAMT reaction has important implications beyond creatine production:

GAMT reaction: GAA + SAM → Creatine + SAH (S-adenosylhomocysteine)

Because this reaction consumes so many methyl groups, supplementing with exogenous creatine reduces the burden on GAMT and frees methyl groups for other essential methylation reactions, including DNA methylation, phospholipid synthesis, and neurotransmitter production.

This “methyl-sparing” effect is one of the lesser-known but significant benefits of creatine supplementation.

Relevance to Creatine Supplementation

When you supplement with creatine, you effectively bypass the need for GAMT activity.

This has two benefits: your muscles receive more creatine than endogenous production alone can provide, and your body conserves methyl groups for other important biological processes.

For vegetarians and vegans, who obtain little dietary creatine, GAMT works harder to maintain creatine levels.

Supplementation is particularly valuable for these groups as it reduces metabolic strain on the methylation system.

Sources & References

Full citations available in our Research Library.

Frequently Asked Questions

What does the GAMT enzyme do?

GAMT (guanidinoacetate N-methyltransferase) catalyzes the second and final step of creatine biosynthesis. It converts guanidinoacetate (GAA) into creatine by adding a methyl group from S-adenosylmethionine (SAM). This reaction occurs in the liver.

What is GAMT deficiency?

GAMT deficiency is a rare autosomal recessive disorder that impairs creatine synthesis. It causes intellectual disability, seizures, and movement disorders. Unlike creatine transporter deficiency, GAMT deficiency can be treated with oral creatine supplementation combined with dietary restriction of arginine and ornithine supplementation.

Why does GAMT activity matter for overall health?

GAMT uses approximately 40% of all SAM-derived methyl groups in the body, making creatine synthesis the largest consumer of methyl donors. Supplementing with creatine reduces the demand on GAMT, freeing methyl groups for other critical processes like DNA methylation, neurotransmitter synthesis, and homocysteine metabolism.

Reviewed by T. Dinaiz, BSc (Molecular Biology), MSc (Biotechnology)

Reviewed against peer-reviewed research · Our editorial policy