Collagen
James Carmichael, 2008
Introduction
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The most abundant extra-cellular protein in the human body
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Makes up 30% of total body protein
Synthesis
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Protein synthesis on the endoplasmic reticulum forms three polypeptide chains that make up protocollagen
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Hydroxylated to procollagen
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Procollagen is then converted to a triple helix and then secreted from the cell
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Once secreted procollagen pepsidases split off the terminal endieces to allow polymerisation.
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It is these crosslinks that determine the tensilestrength.
Structure
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A collagen molecule is a triple helix made up of 3 alpha chains (2 alpha 1 and 1 alpha 2)
Types of Collagen:
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bone, tendon, meniscus, annulus of intervertebral disc, skin
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Articular cartilage, Nucleus propulsus
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Skin, Blood vessel
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Basement Membrane
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Articular cartilage (small amounts)
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Thethers condrocytes to the ECM in articular cartilage
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Epithelial Basement Membrane
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Epithelial basement membrane
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Articular Cartilage (small amounts)
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Hypertrophic cartilage
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Articular Cartilage (small amounts)
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Tendon
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Endothelial cells
These collagens are broadly divided into 3 classes
Class 1:
These have long chains and are the orthopaedic collagens
Types I, II and III
Class 2:
Basement membrane components
Types IV, VII and VIII
Class 3:
Miscellaneous
Types VI, IX and X
Collagen Function
The function collagen performs is related to its structure and is subtly different in different tissues
Type 1 Collagen:
Type 1 collagen is usually responsible for resisting tensile forces. In this manner it contributes to the function of the tissues it is found in.
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