Catalysis of the transfer of an N-acetyl-D-glucosamine residue from UDP-N-acetyl-D-glucosamine to the 4-position of a mannose linked alpha-1,6 to the core mannose of high-mannose oligosaccharides produced by Dictyostelium discoideum.
UDP-N-acetyl-D-glucosamine:high-mannose-oligosaccharide beta-1,4-N-acetylglucosaminyltransferase activity