<p>Phosphoribosylglycinamide formyltransferase (<db_xref db="EC" dbkey="2.1.2.2"/>) (GART) [<cite idref="PUB00000327"/>] catalyses the third step in <i>de novo</i> purine biosynthesis, the transfer of a formyl group to 5'-phosphoribosylglycinamide. In higher eukaryotes, GART is part of a multifunctional enzyme polypeptide that catalyses three of the steps of purine biosynthesis. In bacteria, plants and yeast, GART is a monofunctional protein of about 200 amino-acid residues.</p><p>In the <taxon tax_id="562">Escherichia coli</taxon> enzyme, an aspartic acid residue has been shown to be involved in the catalytic mechanism. The region around this active site residue is well conserved in GART from prokaryotic and eukaryotic sources.</p><p>Mammalian formyltetrahydrofolate dehydrogenase (<db_xref db="EC" dbkey="1.5.1.6"/>) [<cite idref="PUB00002683"/>] is a cytosolic enzyme responsible for the NADP-dependent decarboxylative reduction of 10-formyltetrahydrofolate into tetrahydrofolate. It is a protein of about 900 amino acids consisting of three domains; the N-terminal domain (200 residues) is structurally related to GARTs.</p><p>E. coli methionyl-tRNA formyltransferase (<db_xref db="EC" dbkey="2.1.2.9"/>) (gene fmt) [<cite idref="PUB00002186"/>] is the enzyme responsible for modifying the free amino group of the aminoacyl moiety of methionyl-tRMA(fMet). The central part of fmt seems to be evolutionary related to GART's active site region.</p><p>This signature contains the Asp active site residue.</p> Phosphoribosylglycinamide formyltransferase, active site