Abstract: A novel gene defining a novel enzyme in the UDP-D-galactose: beta-N-acetylglucosamine/beta-N-acetylgalactosamine beta 1,3galactosyltransferase family, termed beta3Gal-T5, with unique enzymatic properties is disclosed. The enzymatic activity of beta3Gal-T5 is shown to be distinct from that of previously identified enzymes of this gene family. The invention discloses isolated DNA molecules and DNA constructs encoding beta3Gal-T5 and derivatives thereof by way of amino acid deletion, substitution or insertion exhibiting beta3Gal-T5 activity, as well as cloning and expression vectors including such DNA, cells transfected with the vectors, and recombinant methods for providing beta3Gal-T5. The enzyme beta3Gal-T5 and beta3Gal-T5-active derivatives thereof are disclosed, in particular soluble derivatives comprising the catalytically active domain of beta3Gal-T5.