Extracellular matrix Flashcards

1
Q

What is the extracellular matrix composed of?

A

-Collagens
-Elastin
-Proteoglycans
Glycoproteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is collagen?

A
  • Major structural protein
  • Three peptide 𝛂-chains wrapped around each other
    • 3 same homotrimer
    • 3 different heterotrimer
  • Right hand triple helix
    • Glycine essential
    • Stabilised by Hydrogen bonds
    • Proline and OH-proline provide rigidity and stability
  • 3rd amino acids glycine (Gly-X-Y)n
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is type I collagen?

A

[𝛂1(I)2𝛂2(I)]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is tendon tensile strength determined by?

A

Parallel type I collagen fibril bundles - forms lamellae in bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is cartilage made of?

A

Type II collagen and aggrecan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the structure of cartilage?

A

See diagram.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Elastin

A

Structural protein
Single gene product
Alternating hydrophobic and cross-linking domains
Low turnover
Extremely resilient
Undergoes many cycles of extension and recoil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Fibrillins

A

Structural proteins
major component of elastic fibres
-large glycoproteins
Beaded string microfibril
Interacts with - elastin, matrix associated glycoproteins, fibulins, latent transforming growth factor beta binding proteins
Regulatory role - TGFbeta storage and activation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Proteoglycans

A

Diverse family of proteins
contain at least one glycosaminoglycan (GAG) chain
Extracellular Matrix proteoglycans
- hold water in tissues
- Confer material properties; viscoelasticity and resistance to compression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

GAGs

A
occupy large space and form hydrated gels
-unbranched polysaccharides
-repeating diaccharide units
Negatively charged
e.g. Hyaluronan 
Four types of sulphated GAG
-Chondroitin Sulphate
-Dermatan Sulphate
-Heparan Sulphate
-Keratan Sulphate
Only sulfated bind to proteoglycan
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Aggrecan

A
Major proteoglycan in cartilage
-huge multimeric aggregates
Link stabolises binding to Hyaluronan
highly hydrophobic
Huge turgor pressure in tissue - resists compresion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Small Leucine Rich Proteoglycans (SLRP)

A
Proteoglycans
bridge adjacent collagen fibrils
-GAG-GAG interactions
-maintain separation between fibrils
-e.g. corneal transparency

E.g. Lumican - thinner collagen fibrils

e. g. Decorin - proteotypical SLRP
- Binds collagen fibrils at specific sites
- inhibits collagen type I fibrillogenesis in vitro

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are non-sturctural functions of ECM?*

A

Regulate cell and growth factor activity

Proteoglycans Regulate TGFbeta activity in ECM
Fibroglast growth factor (FGF) signalling
-bind and present ligand (FGF) to receptor
-Receptors dimerise and phosphorylate receptor tyrosine kinase (TK) - transcription regulation
- Activation of RAS/ERK pathway

TGFbeta isolated in ECM by SLRP
Regulation of TGFbeta activity by the ECM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly