Enables N-acetylgalactosamine 4-O-sulfotransferase activity. Predicted to be involved in proteoglycan biosynthetic process and sulfur compound metabolic process. Predicted to act upstream of or within carbohydrate metabolic process. Predicted to be located in Golgi apparatus and membrane. Predicted to be integral component of membrane. Orthologous to human CHST9 (carbohydrate sulfotransferase 9). [provided by Alliance of Genome Resources, Apr 2022]