Protein Domain : GTP cyclohydrolase I, feedback regulatory protein IPR009112

Type	Family
Description	GTP cyclohydrolase I feedback regulatory protein (GFRP) in mammals helps regulate the biosynthesis of tetrahydrobiopterin through the feedback inhibition of the rate-limiting enzyme GTP cyclohydrolase I (GTPCHI). Tetrahydrobiopterin is the cofactor required for the hydroxylation of aromatic amino acids. The crystal structure of GFRP reveals that the protein forms a homopentamer [ ]. In the presence of phenylalanine, the stimulatory complex consists of a GTPCHI decamer sandwiched by two GFRP pentamers, which is thought to enhance GTPCHI activity by locking the enzyme in the active state []. The structure of GFRP consists of two alpha/beta layers arranged beta(2)-α-β(2)-α-β(2), with antiparallel β-sheets in the order 342165.
Short Name	GTP_CycHdrlase_I_reg