Notes: Dopamine 4-O-sulfate is an inactive metabolite of the catecholamine dopamine (Item No. 21992).{57651,64393} It is formed from dopamine by the sulfotransferase (SULT) isoform SULT1A3.{57652} Dopamine 4-O-sulfate is found at lower levels in the brain and circulation than dopamine 3-O-sulfate (Item No. 34129).{57651,57652}