There are several types of glycosylation, although the first two are the most common.
* In N-glycosylation, sugars are attached to nitrogen, typically on the amide side-chain of asparagine.
* In O-glycosylation, sugars are attached to oxygen, typically on serine or threonine, but also on tyrosine or non-canonical amino acids such as hydroxylysine and hydroxyproline.
* In P-glycosylation, sugars are attached to phosphorus on a phosphoserine.
* In C-glycosylation, sugars are attached directly to carbon, such as in the addition of mannose to tryptophan.
* In S-glycosylation, a beta-GlcNAc is attached to the sulfur atom of a cysteine residue.
* In glypiation, a GPI glycolipid is attached to the C-terminus of a polypeptide, serving as a membrane anchor.
* In glycation, also known as non-enzymatic glycosylation, sugars are covalently bonded to a protein or lipid molecule, without the controlling action of an enzyme, but through a Maillard reaction.