InterPro domain: IPR000965

Gamma-glutamyl phosphate reductase ( 1.2.1.41 ) (GPR) is the enzyme that catalyses the second step in the biosynthesis of proline from glutamate, the NADP-dependent reduction of L-glutamate 5-phosphate into L-glutamate 5-semialdehyde and phosphate. In bacteria (gene proA) and yeast [ 1 ] (gene PRO2), GPR is a monofunctional protein, while in plants and mammals, it is a bifunctional enzyme (P5CS) [ 2 ] that consists of two domains, an N-terminal glutamate 5-kinase domain ( 2.7.2.11 ) and a C-terminal GPR domain. In humans, the P5CS (ALDH18A1), an inner mitochondrial membrane enzyme, is essential to the de novo synthesis of the amino acids proline and arginine [ 3 ]. Tomato (Lycopersicon esculentum) has both the prokaryotic-like polycistronic operons encoding GK and GPR (PRO1, ALDH19) and the full-length, bifunctional P5CS (PRO2, ALDH18B1) [ 4 ].

This entry represents the C-terminal GPR domain of the gamma-glutamyl phosphate reductase.

1. Sequencing of a 35.71 kb DNA segment on the right arm of yeast chromosome XV reveals regions of similarity to chromosomes I and XIII. Yeast 12, 1021-31
2. A bifunctional enzyme (delta 1-pyrroline-5-carboxylate synthetase) catalyzes the first two steps in proline biosynthesis in plants. Proc. Natl. Acad. Sci. U.S.A. 89, 9354-8
3. Molecular enzymology of mammalian Delta1-pyrroline-5-carboxylate synthase. Alternative splice donor utilization generates isoforms with different sensitivity to ornithine inhibition. J. Biol. Chem. 274, 6754-62
4. Comparative analysis of the regulation of expression and structures of two evolutionarily divergent genes for Delta1-pyrroline-5-carboxylate synthetase from tomato. Plant Physiol. 118, 661-74