Extracellular Matrix Flashcards
What is the extracellular matrix:
An extracellular space filled with a network of macromolecules
Tissue organisation
In epitheal: there is a thin layer of ECM with tightly bound cells (mechanical stresses transmitted cell to cell here)
In connective tissue: there is alot of componentslike collagen fibers with few cells like fat cells immune cells (mechanical stresses transmitted directly to matrix here)
Tissue organisation
In epitheal: there is a thin layer of ECM with tightly bound cells (mechanical stresses transmitted cell to cell here)
In connective tissue: there is alot of componentslike collagen fibers with few cells like fat cells immune cells (mechanical stresses transmitted directly to matrix here; it helps resistance to compressive forces (elasticity) and strength
Types of connective tissue
Tendon - ropelike, high tensile strength (collagen fibrils)
Blood vessel walls – resilient, flexible (elastic fibres)
Cartilage – tensile strength and elastic properties (collagen and proteoglycan aggrecan)
Bone – rigid and incompressible (calcified collagen)
Vitreous content of eye - transparent jelly (collagen fibres and hyaluronan
What are the TWO components of the matrix?
1) Glycosaminoglycans (GAGS) - linked to protein, ie a proteoglycan
2) Fibrous proteins like collagen
What is fribrinogen an example of?
adhesive glycoproteins which act as adapters, providing molecular interactions by binding matrix proteins, cells or both
Describe GAGS?
1) UNBRANCHED polysaccharide chains made up od wo sugar repeats (disaccharides - aminosugar and uronic sugar.
It is highly negative due to carboxyl groups and so water is attracted to them (water reabsorption)
It has four main groups.
An example of GAG is Hyaluronan
This has a long chainacting as a NON OMPRESSIBLE SPACE FILLER
It makes pressure by attracting water
What is the structure of a protoglycan eg, betaglycan, aggrecan in cartilage
GAG attached to a link tetrasaccharide with is atached to the serine of a protein via the glycsyl transferase in E.R
What is major fibrous extracellular matrix component?
Collagens. (in skin and bone) various forms expressed in different tissues.
Some form fibrils in connective tissue via INTRERMOLECULAR COVALENT CROSS LINKS (lysines and hydroxysines)
Describe the structure of collagen.
alpha chains form trimers of three tightly bound chains
chains fold into a helix with 3 aa per turn.
Trimers to fibrils to fibers
Describe the structure of collagen. (5 fibril forming types)
alpha chains form trimers of three tightly bound chains
chains fold into a helix with 3 aa per turn.
Trimers to fibrils to fibers
How do Fibril-associated collagens compare to normal ones?
don’t form fibrils
- non-helical domains interrupt triple helix, making molecule more flexible
- retain propeptides, so don’t aggregate into fibrils
bind to fibrils of fibrillar collagens
- mediate fibril interactions with each other and with other ECM molecules to determine fibril organisation
Describe elastin.
- hydrophobic protein
- secreted as tropoelastin, then highly CROSSLINKED to form network of fibres and sheets
elastic fibres also covered in MICROFIBRILS – made from other glycoproteins e.g. fibrillin
Describe elastin.
- hydrophobic protein
- secreted as tropoelastin, then highly CROSSLINKED to form network of fibres and sheets
elastic fibres also covered in MICROFIBRILS – made from other glycoproteins e.g. fibrillin
forms elastic fibers for resilliance.
