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Abstract

A novel gene defining a novel enzyme in the UDP-D-galactose: β-N-acetylglucosamine / β-N-acetylgalactosamine βgalactosyltransferase family, termed βGal-T, with unique enzymatic properties is disclosed. The enzymatic activity of βGal-Tis shown to be distinct from that of previously identified enzymes of this gene family. The invention discloses isolated DNA molecules and DNA constructs encoding βGal-Tand derivatives thereof by way of amino acid deletion, substitution or insertion exhibiting βGal-Tactivity, as well as cloning and expression vectors including such DNA, cells transfected with the vectors, and recombinant methods for providing βGal-T. The enzyme βGal-Tand βGal-T-active derivatives thereof are disclosed, in particular soluble derivatives comprising the catalytically active domain of βGal-T. Further, the invention discloses methods of obtaining βgalactosyl glycosylated saccharides, glycopeptides or glycoproteins by use of an enzymatically active βGal-Tprotein or, fusion protein thereof or by using cells stably transfected with a vector including DNA encoding an enzymatically active βGal-Tprotein as an expression system for recombinant production of such glycopeptides or glycoproteins. Also a method for the identification of DNA sequence variations in the βGal-Tgene by isolating DNA from a patient, amplifying βGal-T-coding exons by PCR, and detecting the presence of DNA sequence variation, are disclosed.