As has been stated, IgGs have an oligosaccharide bound to each heavy chain. Here we can see it in detail:
Let's isolate a single oligosaccharide chain, together with the asparagine residue it is linked to.
Colour by residue: Asn, galactose, N-acetylglucosamine, manose, fucose N-acetyl groups.
This is the oligosaccharide structure: