TPH2

The enzyme Tryptophan hydroxylase 2, also known as TPH2, is an isozyme of is_associated_with::Tryptophan hydroxylase found in vertebrates. In humans TPH2 is primarily expressed in the serotonergic neurons of the brain, with the highest expression in the raphe nucleus of the midbrain. Until the discovery of TPH2 in 2003, serotonin levels in the central nervous system were believed to be regulated by serotonin synthesis in peripheral tissues, in which Tryptophan hydroxylase is the dominant form.