In enzymology, glutamate-5-semialdehyde dehydrogenase () is an enzyme that catalyzes the chemical reaction
The three substrates of this enzyme are L-glutamate-5-semialdehyde, oxidised nicotinamide adenine dinucleotide phosphate (NADP<sup>+</sup>) and phosphate (P<sub>i</sub>). Its products are L-ó-glutamyl phosphate, reduced NADPH, and a proton.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the aldehyde or oxo group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is L-glutamate-5-semialdehyde:NADP+ 5-oxidoreductase (phosphorylating). Other names in common use include beta-glutamylphosphate reductase, gamma-glutamyl phosphate reductase, beta-glutamylphosphate reductase, glutamate semialdehyde dehydrogenase, and glutamate-gamma-semialdehyde dehydrogenase. This enzyme participates in urea cycle and metabolism of amino groups.
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes , , and .