SULT1B1 enzyme in humans is encoded by the SULT1B1 gene. SULT1B1 holds a binding site for 3-prime-phosphoadenosine 5-prime-phosphosulfate， a sulfate donor， in addition to a cysteine residue conserved in the ST1 gene family of sulfotransferases. Sulfotransferases like SULT1B1 catalyze the biotransformation of a great amount of endogenous amalgams such as bile acids， neurotransmitters， steroids， and thyroid hormones， in addition to drugs and xenobiotics.
