Guanidinoacetate methyltransferase (GAMT; ) catalyses the last step of creatine biosynthesis. In humans, GAMT is believed to be the major enzyme involved in the metabolic conversion of S-adenosylmethionine (SAM) to S-adenosylhomocycteine (SAH). GAMT is found in abundance in the liver of all vertebrates. The crystal structure of a truncated version of GAMT shows that it exists as a dimer [], and the structure can be viewed as a ternary complex between protein arginine methyltransferase (one subunit) complexed with a protein substrate (the partner subunit) and the product SAH []. Deficiency of GAMT in the liver causes a hereditary disease with extra pyramidal motor disorder and extremely low concentrations of creatine in the brain, serum and urine [].
This domain is found in arginine N-methyltransferase 2, a delta-N-monomethylarginine transferase which monomethylates 'Arg-67' of ribosomal protein L12 []. The domain is also found in guanidinoacetate N-methyltransferase (GAMT), defects in which cause GAMT deficiency, an autosomal recessive disorder [].
