Guanidinoacetate N-methyltransferase (EC 2.1.1.2) is an enzyme that catalyzes the chemical reaction and is encoded by gene GAMT located on chromosome 19p13.3.^[5]

GAMT
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 3ORH
Identifiers
Aliases	GAMT, CCDS2, HEL-S-20, PIG2, TP53I2, guanidinoacetate N-methyltransferase
External IDs	OMIM: 601240 MGI: 1098221 HomoloGene: 32089 GeneCards: GAMT
Gene location (Human) Chr. Chromosome 19 (human)[1] Band 19p13.3 Start 1,397,026 bp[1] End 1,401,570 bp[1]
Gene location (Mouse) Chr. Chromosome 10 (mouse)[2] Band 10 C1|10 39.72 cM Start 80,093,985 bp[2] End 80,096,846 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in right lobe of liver gastrocnemius muscle triceps brachii muscle vastus lateralis muscle thoracic diaphragm biceps brachii body of pancreas corpus epididymis tibialis anterior muscle deltoid muscle Top expressed in left lobe of liver adrenal gland yolk sac gallbladder esophagus triceps brachii muscle proximal tubule temporal muscle internal carotid artery lens More reference expression data BioGPS More reference expression data
Gene ontology Molecular function methyltransferase activity transferase activity guanidinoacetate N-methyltransferase activity S-adenosylmethionine-dependent methyltransferase activity Cellular component cytoplasm cytosol nucleus Biological process muscle contraction regulation of multicellular organism growth methylation spermatogenesis animal organ morphogenesis creatine metabolic process creatine biosynthetic process S-adenosylhomocysteine metabolic process S-adenosylmethionine metabolic process Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 2593 14431 Ensembl ENSG00000130005 ENSMUSG00000020150 UniProt Q14353 O35969 RefSeq (mRNA) NM_138924 NM_000156 NM_010255 NM_001347119 RefSeq (protein) NP_000147 NP_620279 NP_001334048 NP_034385 Location (UCSC) Chr 19: 1.4 – 1.4 Mb Chr 10: 80.09 – 80.1 Mb PubMed search [3] [4]
Wikidata
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S-adenosyl-L-methionine + guanidinoacetate ${\displaystyle \rightleftharpoons }$ S-adenosyl-L-homocysteine + creatine

Thus, the two substrates of this enzyme are S-adenosyl methionine and guanidinoacetate, whereas its two products are S-adenosylhomocysteine and creatine.

This enzyme belongs to the family of transferases, specifically those transferring one-carbon group methyltransferases. The systematic name of this enzyme class is S-adenosyl-L-methionine:N-guanidinoacetate methyltransferase. Other names in common use include GA methylpherase, guanidinoacetate methyltransferase, guanidinoacetate transmethylase, methionine-guanidinoacetic transmethylase, and guanidoacetate methyltransferase. This enzyme participates in glycine, serine and threonine metabolism and arginine and proline metabolism.

The protein encoded by this gene is a methyltransferase that converts guanidoacetate to creatine, using S-adenosylmethionine as the methyl donor. Defects in this gene have been implicated in neurologic syndromes and muscular hypotonia, probably due to creatine deficiency and accumulation of guanidinoacetate in the brain of affected individuals. Two transcript variants encoding different isoforms have been described for this gene.^[5]