Lysyl hydroxylase is a membrane-bound homodimeric protein
localized to the cisternae of the endoplasmic reticulum. The enzyme
(cofactors iron and ascorbate) catalyzes the hydroxylation of lysyl
residues in collagen-like peptides. The resultant hydroxylysyl
groups are attachment sites for carbohydrates in collagen and thus
are critical for the stability of intermolecular crosslinks. Some
patients with Ehlers-Danlos syndrome type VI have deficiencies in
lysyl hydroxylase activity.
