This presentation on heritable disorders of collagen,
has been prepared by Heather Yeowell,
of Duke University Medical Center, Division of Dermatology.
Firstly, what are collagens?
They comprise of family of
extracellular matrix proteins that has tremendous tensile strength,
and play a dominant role in maintaining the structure of various tissues.
Other important functions are their involvement in
cell adhesion, chemotaxis and migration,
and their dynamic interplay with cells to regulate tissue remodeling during growth,
differentiation, morphogenesis and wound healing.
In regard to the collagen family and structure,
the collagen family now includes at least 28 distinct members,
with 46 different alpha chains.
There were more than 20 additional proteins that have collagen-like domains.
Collagens are the main extracellular proteins,
that for instance comprise over 70 percent of dry weight of dermis.
The basic structure of the collagens,
is that they consist of three polypeptide or alpha chains,
wound in a triple helix.
The chains may be identical or different.
For example, the molecule can contain two or even three different alpha chains.
The chains contain a triple helical domain of repeating Gly-X-Y sequence.
The smallest amino acid glycine,
is in the interior of the helix,
and is thus essential to maintain the structure of the triple helix.
Any other amino acid can occupy the X-Y position,
but proline is often at position X,
and hydroxyProline, or hydroxyLysine,
are only found at position Y.
The collagen presentation will begin with