Collagen VII is the major molecular constituent of anchoring fibrils in the skin. Collagen VII is synthesized as three identical pro-alpha1(VII) polypeptide chains, which are hydroxylated and glycosylated in a coordinated manner and then fold into triple-helical procollagen VII in the endoplasmic reticulum (ER). Mature collagen VII undergoes a multistep fibril polymerization process to form the anchoring fibrils. Mutant pro-alpha1(VII) polypeptide chains or procollagen VII molecules do not pass the ER quality control and are retained in the ER or designated for ubiquitin-proteasome degradation resulting in reduced amounts of collagen VII in the skin. [from
HPO]