ANHB3323 Lecture Notes - Lecture 17: Ultimate Tensile Strength, Keratinocyte, Muscle
3 Jun 2018
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LECTURE SEVENTEEN: Extracellular Matrix
ECM of Animals:
• Cells → fibroblast
• ECM
o Proteins → collagen → type iV, fibrillar
o Glycoproteins → laminin, nidogen, fibronectin
o Proteyglycans/GAGs → hyaluronan, perlecan, aggrecan
GAG (Glycosaminoglycan):
• Unbranched polysaccharide chains with repeating disaccharide units
• 4 main groups
o Hyaluronan
o Chondoritin sulfate
o Dermatan sulfate
o Keratan sulphate
• Too stiff to fold into globular structures
• Strongly hydrophilic
• Huge volume relative to mass → space filler
• Form hydrated gels even at the low concentrations
• Compressive force vs. stretching force
Proteoglycans:
• All GAGs covalently attached to protein except hyaluronan →
proteoglycans
• Protein + sugar
• Proteoglycan → at least 1 sugar side chain must be a GAG → large
proportion of carbohydrate
• Glycoprotein → relatively shorted branched oligosaccharide → small
proportion of carbohydrate
• Limitless heterogeneity
• Can be small or large
Collagen:
• Major proteins of ECM
• Most abundant protein in mammals → 25% of total protein mass
• Gly-X-Y-a chain
o X = proline
o Y = hydroxyproline
• Left handed → 1000 amino acids long → glycine every third AA
• Triple-stranded helical rod
• Small glycine → interior or the triple hex
• Human genome contains 42 distinct genes coding for different collagen a
chains but only ~ 40 types of collagen
• Fibril forming
o Type I → bone, tendons, ligaments
o Type II → cartilage
o Type III → skin, blood vessels, internal organs
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