In enzymology, a galactosylceramide sulfotransferase (EC 2.8.2.11) is an enzyme that catalyzes the chemical reaction

3'-phosphoadenylyl sulfate + a galactosylceramide ${\displaystyle \rightleftharpoons }$ adenosine 3',5'-bisphosphate + a galactosylceramidesulfate

Thus, its two substrates are 3'-phosphoadenylyl sulfate and galactosylceramide, and its two products are adenosine 3',5'-bisphosphate and galactosylceramidesulfate.

It belongs to the family of transferases, specifically the sulfotransferases, which transfer sulfur-containing groups. The systematic name of this enzyme class is 3'-phosphoadenylyl-sulfate:galactosylceramide 3'-sulfotransferase. Other names in common use include GSase, 3'-phosphoadenosine-5'-phosphosulfate-cerebroside sulfotransferase, galactocerebroside sulfotransferase, galactolipid sulfotransferase, glycolipid sulfotransferase, and glycosphingolipid sulfotransferase. This enzyme participates in sphingolipid metabolism.

• McKhann GM, Levy R, Ho W (1965). "Metabolism of sulfatides. I. The effect of galactocerebrosides on the synthesis of sulfatides". Biochem. Biophys. Res. Commun. 20 (2): 109–13. doi:10.1016/0006-291X(65)90331-1. PMID 5850675.
• Sakakibara N, Gasa S, Kamio K, Makita A, Koyanagi T (1989). "Association of elevated sulfatides and sulfotransferase activities with human renal cell carcinoma". Cancer Res. 49 (2): 335–9. PMID 2562926.