L-arginine:glycine amidinotransferase, inosamine-phosphate amidinotransferase and similar proteins
This family contains amidinotransferase enzymes known to catalyze the transfer of the amidino group from a donor molecule (usually arginine) to an acceptor molecule bearing a primary amine. They are widespread in nature, occurring in essential metabolic pathways in eukaryotes as well as in biosynthetic pathways for antibiotics and virulence factors in prokaryotes. This family includes L-arginine:glycine amidinotransferase (EC 2.1.4.1; also called glycine amidinotransferase, arginine-glycine amidinotransferase, or arginine-glycine transamidinase), inosamine-phosphate amidinotransferase (EC 2.1.4.2; also called inosamine amidinotransferase, inosamine-P amidinotransferase, or scyllo-inosamine-4-phosphate amidinotransferase or L-arginine:inosamine phosphate amidinotransferase), and similar proteins. L-arginine:glycine amidinotransferase (AT or AGAT) catalyzes the committed step in creatine biosynthesis by formation of guanidinoacetic acid, the immediate precursor of creatine. Inosamine-phosphate amidinotransferases catalyze two nonconsecutive transamidination reactions in the biosynthesis of the streptomycin family of antibiotics. This family also includes L-arginine:inosamine-phosphate Streptomyces griseus amidinotransferase StrB1, which is structurally similar to human L-arginine:glycine amidinotransferase; AT and StrB1 share conserved residues involved in substrate binding and catalysis at equivalent topological positions, suggesting a similar reaction mechanism among amidinotransferases.
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