Catalyzes the transfer of sulfate to position 4 of the N-acetylgalactosamine (GalNAc) residue of chondroitin. Chondroitin sulfate constitutes the predominant proteoglycan present in cartilage and is distributed on the surfaces of many cells and extracellular matrices. Can also sulfate Gal residues in desulfated dermatan sulfate. Preferentially sulfates in GlcA->GalNAc unit than in IdoA->GalNAc unit. Does not form 4, 6-di-O-sulfated GalNAc when chondroitin sulfate C is used as an acceptor. n 3'-phosphoadenylyl sulfate + chondroitin beta-D-glucuronate = n adenosine 3',5'-bisphosphate + chondroitin 4'-sulfate + n H(+) Predominantly expressed in brain and kidney. Also expressed at weaker level in heart, spleen and lung. Expressed in developing chondrocytes. First expressed at day 9.75 of embryogenesis in the apical ectodermal ridge (AER) of the developing limb buds and at the edges of branchial arches 1 and 2. Also expressed in the ventral neural tube, notochord and sympathetic ganglia and the mesonephric tubules of the developing kidneys. In the heart, it is expressed in the myocardium of the atrium and in the endocardial cushions of both the developing inflow tract and the atrioventricular valves. At day 15, it is expressed in the cartilage of developing bones, in vertebrae and cartilage of the trachea as well as in the thymus. In the forelimb, it is expressed in all developing bones, but absent from developing joint regions and was down-regulated in chondrocytes beginning to undergo mineralization, such as in the center of the ulna. At day 15, no expression in the neural tube is observed. In the heart at day 15, it is still expressed in the atrial valve, the atrioventricular valves and in the myocardium of the atrium, while in the kidney, it is expressed in the collecting tubules as well as in Bowman capsule. Interestingly, the liver displays a punctate expression at day 15. Also expressed in tooth primordia, hair follicles and mammary glands. By BMP2, suggesting it is a target of BMP signaling. N-glycosylated; required for activity and stability. Belongs to the sulfotransferase 2 family.