In humans, these genes are located on chromosomes 11 and 12 and encode two different homologous enzymes TPH1 and TPH2 (sequence identity 71%).
Tryptophan | Steroid 11-beta-hydroxylase | Tryptophan dimethylallyltransferase | 8-dimethylallylnaringenin 2'-hydroxylase | 7alpha-hydroxycholest-4-en-3-one 12alpha-hydroxylase | 21-Hydroxylase |