L-glutamate 5-semialdehyde

1. L-ornithine + 2-oxoglutarate = L-glutamate 5-semialdehyde + L-glutamate

Catalysed by OAT

1. L-glutamate 5-semialdehyde + phosphate + NADP(+) = L-glutamyl 5-phosphate + NADPH + H(+)

Catalysed by ALDH18A1

1. L-ornithine + 2-oxoglutarate = L-glutamate 5-semialdehyde + L-glutamate
2. D-histidine(in) + L-ornithine(out) + H(+)(in) = D-histidine(out) + L-ornithine(in) + H(+)(out)

Catalysed by OAT, SLC25A2inner side of the membrane, outer side of the membraneOne of 2 routes

1. L-ornithine + 2-oxoglutarate = L-glutamate 5-semialdehyde + L-glutamate
2. L-homoarginine(in) + L-ornithine(out) = L-homoarginine(out) + L-ornithine(in)

Catalysed by OAT, SLC25A2inner side of the membrane, outer side of the membraneOne of 2 routes

1. L-ornithine + 2-oxoglutarate = L-glutamate 5-semialdehyde + L-glutamate
2. transport of ornithine and tryptophan (cytosol to extracellular)
3. beta-carboline hydrolysis

Catalysed by OAT, SLC7A6extracellular space, cytosol

1. L-ornithine + 2-oxoglutarate = L-glutamate 5-semialdehyde + L-glutamate
2. L-ornithine carboxy-lyase (putrescine-forming)
3. acetyl-CoA:putrescine N-acetyltransferase

Catalysed by OAT, ODC1