In enzymology, a steroid N-acetylglucosaminyltransferase (EC 2.4.1.39) is an enzyme that catalyzes the chemical reaction

UDP-N-acetyl-D-glucosamine + estradiol-17alpha 3-D-glucuronoside ${\displaystyle \rightleftharpoons }$ UDP + 17alpha-(N-acetyl-D-glucosaminyl)-estradiol 3-D-glucuronoside

Thus, the two substrates of this enzyme are UDP-N-acetyl-D-glucosamine and estradiol-17alpha 3-D-glucuronoside, whereas its two products are UDP and 17alpha-(N-acetyl-D-glucosaminyl)-estradiol 3-D-glucuronoside.

This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is UDP-N-acetyl-D-glucosamine:estradiol-17alpha-3-D-glucuronoside 17alpha-N-acetylglucosaminyltransferase. Other names in common use include hydroxy steroid acetylglucosaminyltransferase, steroid acetylglucosaminyltransferase, uridine diphosphoacetylglucosamine-steroid, and acetylglucosaminyltransferase.

• Collins DC, Jirku H, Layne DS (1968). "Steroid N-acetylglucosaminyl transferase. Localization and some properties of the enzyme in rabbit tissues". J. Biol. Chem. 243 (11): 2928–33. PMID 5660254.