Human SULT1A3 Recombinant Protein. The human Catecholamine-Sulfating Phenol Sulfotransferase (CSPS) is the only sulfotransferase that catalyses the sulfation of catecholamins, in particular the neurotransmitter dopamine, with high activity. CSPS is required for stimulation by Mn2+ of the sulfating activity and expressed in the human intestine, brain, platelet and other tissues. In the brain it may play a role in regulating the levels of dopamine. It also serves as a detoxifying function in the intestine, where it may detoxify potentially lethal dietary monoamines.