sentences:  In most eukaryotes, GSA is synthesised from the amino acid glutamate by the bifunctional enzyme 1-pyrroline-5-carboxylate synthase(P5CS).The human P5CS is encoded by the "ALDH18A1" gene.The enzyme pyrroline-5-carboxylate reductase converts P5C into proline
  
  In proline degradation, the enzyme proline dehydrogenase produces P5C from proline, and the enzyme 1-pyrroline-5-carboxylate dehydrogenase converts GSA to glutamate.