The function of ENSG00000170340 (B3GNT2, UDP-GlcNAc:betaGal beta-1,3-N-acetylglucosaminyltransferase 2) is as follows. Beta-1,3-N-acetylglucosaminyltransferase involved in the synthesis of poly-N-acetyllactosamine. Catalyzes the initiation and elongation of poly-N-acetyllactosamine chains. Shows a marked preference for Gal(beta1-4)Glc(NAc)-based acceptors (PubMed:9892646). Probably constitutes the main polylactosamine synthase. {ECO:0000269|PubMed:11042166, ECO:0000269|PubMed:18826941, ECO:0000269|PubMed:25279697, ECO:0000269|PubMed:9892646}.