Biosynthesis: overview

Such as other secreted proteins like collagen polypeptides are synthesized through ribosomes on the rough endoplasmic reticulum RER. The polypeptide chain then passes by the Golgi and RER apparatus before being secreted. Along the path it is post-translationally modi?ed:   Lys and Pro residues are carbohydrate and hydroxylated is added in figure. Before secretion three polypeptide chains come together to form a triple-helical structure which is known as procollagen.  Then procollagen is the secreted into the extracellular spaces of the connective tissue where extensions of the polypeptide chains at both the C and N termini and extension peptides are erased through peptidases to form tropocollagen in the Figure. The tropocollagen molecules aggregate and are extensively cross-linked to produce the mature collagen ?ber.