Nutrition in Lactation

What is Collagen
  * Collagen is one of the 3 types of connective tissue fibers produced by fibroblasts.
  * It is the most abundant protein found in mammals and is found in the extracellular matrix of various tissues and organ systems in the body including: loose connective tissue, bone, tendons, skin, blood vessels, and the cornea.
Collagen Synthesis
  * Collagen synthesis and assembly into fibrils occurs via a series of intracellular and extracellular events:

Intracellular events
      * Under the direction of mRNA, various alpha chains of preprocollagen are encoded for synthesis at the rough endoplasmic reticulum (RER). Preprocollagen as the name suggests is a precursor of collagen.
      * Certain proline and lysine residues of the growing polypeptide chain are hydroxylated within the RER.   Specific enzymes called hydroxylases catalyze this reaction with the help of Vitamin C as a cofactor.
      * The third step involves the addition of sugar molecules (glycosylation) to specific hydroxylysine residues within the RER.
      * Propeptides regulate the formation of procollagen formation in the RER.   The three alpha chains on procollagen align and coil into a triple helix.
      * Procollagen is then transported to the Golgi complex where carbohydrates are added. This completes the molecule’s oligosaccharide side chains.
      * Secretory vesicles from the Golgi complex guide procollagen to the cell surface along microtubules. Secretion of procollagen then occurs via exocytosis.
Extracellular events
  * Procollagen peptidases catalyze the cleavage of procollagen, which yields tropocollagen, also known as collagen.
  * Self-assembly of tropocollagen occurs as insoluble tropocollagen molecules aggregate near the cell surface.
      * Types I, II, III, V, and VII collagen fibrils are produced. Fibrils, which are highly organized polymers, are the result of collagen biogenesis.
      * Cross-linking between adjacent tropocollagen molecules... [continues]

Read full essay