Sulfotransferase Family Cytosolic 1B Member 1 (SULT1B1) is a cytosolic enzyme that belongs to the Sulfotransferase 1 family. Human SULT1B1 is a 296 amino acid protein that is highly expressed in the liver, peripheral blood leukocytes, colon, small intestine, and spleen. SULT1B1 utilizes 3'-phospho-5'-adenylyl sulfate (PAPS) as sulfonate donor, and it can catalyze the sulfate conjugation of many hormones, neurotransmitters, drugs, and xenobiotic compounds.