Beta-1,3-N-acetylglucosaminyltransferase that plays a key role in the synthesis of lacto- or neolacto-series carbohydrate chains on glycolipids. a beta-D-Gal-(1->4)-beta-D-Glc-(1<->1)-Cer(d18:1(4E)) + UDP-N-acetyl-alpha-D-glucosamine = a beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-beta-D-Glc-(1<->1)-Cer(d18:1(4E)) + H(+) + UDP a neolactoside nLc4Cer(d18:1(4E)) + UDP-N-acetyl-alpha-D-glucosamine = a neolactoside IV(3)-beta-GlcNAc-nLc4Cer(d18:1(4E)) + H(+) + UDP Protein modification; protein glycosylation. Expressed in 2 distinct phases during the embryogenesis. The early phase extends from late blastulation to the completion of epiboly, during which the expression occurs in the superficial layer of the embryos. The second phase of expression starts during mid-segmentation and persists until day 3, during which the expression occurs prominently in the developing lens. Hedgehog signaling is required for expression in embryonic lens. Belongs to the glycosyltransferase 31 family.