Recombinant human Beta-galactoside alpha-2,6-sialyltransferase 1 (ST6Gal I) is expressed in human HEK 293 cells as a glycoprotein with a calculated molecular mass of 43.5 kDa (amino acids 27-406). The DTT-reduced protein migrates as a ~50 kDa polypeptide on SDS-PAGE due to glycosylation. This protein is manufactured in human cells, with no serum. The human cells expression system allows human-like glycosylation and folding, and often supports higher specific activity of the protein. The protein is produced with no artificial tags. Recombinant human Beta-galactoside alpha-2,6-sialyltransferase 1 (ST6Gal I) is expressed in human HEK 293 cells as a glycoprotein with a calculated molecular mass of 43.5 kDa (amino acids 27-406). The DTT-reduced protein migrates as a ~50 kDa polypeptide on SDS-PAGE due to glycosylation. This protein is manufactured in human cells, with no serum. The human cells expression system allows human-like glycosylation and folding, and often supports higher specific activity of the protein. The protein is produced with no artificial tags.