Topic overview

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Three collagen α-chains form a triple helix built around repeating Gly-X-Y sequences. Glycine allows close packing, while hydroxylated residues contribute to helix stability. Collagen synthesis begins in the RER, where processing and modification lead to procollagen formation; after secretion, propeptide cleavage produces tropocollagen. Copper-dependent lysyl oxidase then supports cross-linking, and staggered assembly creates striated fibrils. The major collagen types have distinct tissue distributions, and defects can be associated with conditions such as osteogenesis imperfecta, Ehlers-Danlos syndrome, Alport syndrome, and Goodpasture disease. Collagen is also continually remodeled by matrix metalloproteinases, linking its turnover to healing, fibrosis, and age-related tissue changes.