fig3

Figure 3. Collagen synthesis, secretion into the ECM and cross-linking. Collagens are translated into protein on the ribosomes of the endoplasmic reticulum inside the fibroblast cell. Hydroxylation and glycosylation occur before the 3 helical strands are woven together to form the procollagen species. After secretion into the ECM, the N-terminal and C-terminal ends are cleaved and the tropocollagen units can be assembled into larger structure, which are held together via crosslinked residues between the Lysine aldehyde derivative of one collagen strand and the corresponding hydroxylysine of the opposite strand. (By permission of MINERVA Research Labs Ltd - London)