Beta-1,3-N-acetylglucosaminyltransferase that plays a key role in the synthesis of lacto- or neolacto-series carbohydrate chains on glycolipids, notably by participating in biosynthesis of HNK-1 and Lewis X carbohydrate structures. Has strong activity toward lactosylceramide (LacCer) and neolactotetraosylceramide (nLc(4)Cer; paragloboside), resulting in the synthesis of Lc(3)Cer and neolactopentaosylceramide (nLc(5)Cer), respectively. Probably plays a central role in regulating neolacto-series glycolipid synthesis during embryonic development. {ECO:0000269|PubMed:11283017, ECO:0000269|PubMed:11384981}. This is the function of Ensembl gene identifier ENSG00000176597 (B3GNT5, UDP-GlcNAc:betaGal beta-1,3-N-acetylglucosaminyltransferase 5).