Metabolism of 4-hydroxyproline in animals. AA amino acid, AGT alanine-glyoxylate aminotransferase, Ala alanine, DAO D-amino acid oxidase, Glu glutamate, GO glycolate oxidase, GOT glutamate oxaloacetate transaminase, GR glyoxylate reductase, 4-Hyp 4-hydroxy-proline, 4-OH-2-KG 4-hydroxy-2-ketoglutarate, 3-OH-P5C Δ1-pyrro-line-3-hydroxy-5-carboxylate, LDH lactate dehydrogenase, OAA oxaloacetate, PDH pyruvate dehydrogenase, Pyr pyruvate