Udp-n-acetyl-.alpha.-d-galactosamine: polypeptide

Abstract

A novel gene defining a novel enzyme in the UDP-N-acetyl-.alpha.-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase family, termed GalNAc-T3, with unique enzymatic properties is disclosed. The enzymatic activity of GalNAc-T3 is shown to be distinct from that of two previously identified enzymes of this gene family. The invention discloses isolated DNA molecules and DNA constructs encoding GalNAc-T3 and derivatives thereof by way of amino acid deletion, substitution or insertion exhibiting GalNAc-T3 activity, as well as cloning and expression vectors including such DNA, cells transfected with the vectors, and recombinant methods for providing GalNAc-T3. The enzyme GalNAc-T3 and GalNAc-T3-active derivatives thereof are disclosed, in particular soluble derivatives comprising the catalytically active domain of GalNAc-T3. Further, the invention discloses methods of obtaining N-acetylgalactosamine glycosylated peptides or proteins by use of an enzymically active GalNAc-T3 protein or fusion protein thereof or by using cells stably transfected with a vector including DNA encoding an enzymatically active GalNAc-T3 protein as an expression system for recombinant production of such glycopeptides or glycoproteins. Also a method for the production of a vaccine by modifying the O-glycosylation pattern of an eukaryotic cell, and a method for the identification of DNA sequence variations in the GalNAc-T3 gene by isolating DNA from a patient, amplifying GalNAc-T3-coding exons by PCR, and detecting the presence of DNA sequence variation, are disclosed.