A novel gene defining a novel enzyme in the UDP-D-galactose: b-N-acetyl-glucosamine
-1,4-galactosyltransferase family, termed 4Gal-T2, with unique enzymatic
properties is disclosed. The enzymatic activity of 4Gal-T2 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 4Gal-T2 and
derivatives thereof by way of amino acid deletion, substitution or insertion exhibiting
4Gal-T2 activity, as well as cloning and expression vectors including such
DNA, cells transfected with the vectors, and recombinant methods for providing
4Gal-T2. The enzyme 4Gal-T2 and 4Gal-T2-active derivatives
thereof are disclosed, in particular soluble derivatives comprising the catalytically
active domain of 4Gal-T2. Further, the invention discloses methods of obtaining
-1,4-galactosyl glycosylated saccharides, glycopeptides or glycoproteins
by use of an enzymically active 4Gal-T2 protein or fusion protein thereof
or by using cells stably transfected with a vector including DNA encoding an enzymatically
active 4Gal-T2 protein as an expression system for recombinant production
of such glycopeptides or glycoproteins. Also a method for the identification of
DNA sequence variations in the 4Gal-T2 gene by isolating DNA from a patient,
amplifying 4Gal-T2-coding exons by PCR, and detecting the presence of DNA
sequence variation, are disclosed.
