The function of SULT1C3 (sulfotransferase family 1C member 3, Ensembl gene identifier ENSG00000196228) is as follows. [Isoform 1]: Sulfotransferase that utilizes 3'-phospho-5'- adenylyl sulfate (PAPS) as sulfonate donor. Has sulfotransferase activity towards various substrates, such as bile acids, thyroid hormones and toward xenobiotic compounds such as chloro phenols and hydroxypyrenes. Lithocholic acid appears to be the best substrate among the endogenous compounds tested and 3,3',5,5'-tetrachloro-4,4'- biphenyldiol shows the highest specific activity among the xenobiotic compounds. {ECO:0000269|PubMed:17425406, ECO:0000269|PubMed:17936463, ECO:0000269|PubMed:28992322}. [Isoform 2]: Exhibits weak sulphating activity and only toward chloro phenols (pentachlorophenol and 3,3',5,5'- tetrachloro-4,4'-biphenyldiol). .