Flashcards in Extracellular Matrix Deck (45):
What is the ECM?
Filler and macromolecules (secreted by the cell)
Functions of ECM
1. Cellular division
3 classes of ECM components
1. Structural proteins
3. Adhesive glycoproteins
Examples and functions of structural proteins
Collagens and elastins → provide strength and flexibility
What are they:
Provide matrix for structural proteins
Examples and function of adhesive glycoproteins
Fibronectins and laminins → attach cells to matrix
______ is the most abundant protein in vertebrates and it contains __% of total body protein
Collagen → 25-30%
Tendons and ligaments contain a lot of?
Rigid triple helix of polypeptide chains
1 mm fiber can hold 20 lbs
__ different alpha chains combine to form __ types of collagen
Which are most abundant?
25 different alpha chains → 15 types of collagen
I, II and III most abundant
Type I composes __% of collagen in body
Collagen cross linking function
Strengthens collagen bundle to withstand high stress
Elastin provides flexibility to what tissues?
Elasticity is dependent on what ratio?
Collagen : Elastin
Proteins rich in glycine and proline (no hydroxylation) and elastin molecule (crosslinked between lysines)
Glycoprotein + glycosaminoglycan side chain
Long polysaccharides → 2 monosaccharides in alternating order
Protein with GAGs (up to 95% carbohydrate)
How are proteoglycans classified?
And what are 3 of the most common?
By glycosaminoglycan side chain:
1. Chondroitin sulfate
2. Keratan sulfate
3. Heparin / heparin sulfate
Location of chondroitin sulfate
Cartilage (osteoarthritis implications)
Keratan sulfate locations and function
3. Shock absorption
4. Trap water (>50%x their weight)
1. Lubricates joints
2. Found on surface of migrating cells → facilitates cell migration
What is it:
Family with side chains made of D-glucosamine or L-iduronic acid
Found in every cell of body
What is it:
One member of the heparan sulfate family
Heparan sulfate family functions (other than heparin)
1. Bind growth factors
2. Important role in inflammation
3. Entry of virus into cells (herpes, rabies)
Most common adhesive glycoprotein (contains about 5% carbohydrates)
Family of closely related proteins
Can be soluble, insoluble or partialy soluble → caused by alternative splicing of the same gene
1. Maintain cell shape
2. Possible role in cancer
3. Blood clotting (soluble form)
4. Wound healing → guides immune cells to wound
5. Cell migration
Laminins are mainly located where?
Separates ECM from epithelial cells
Basal lamina roles
1. Structural support
2. Permeability barrier (acts as filter in kidney)
3. Cell migration (may allow migration of cancer cells)
Matrix remodeling is most active at?
Sites of abundance-cellular sources:
1. Cartilage: chondrocytes
2. Bone: osteocytes, osteoblasts
3. Tendon: teniacytes (fibrocytes)
4. Cornea: fibrocytes
Enzymes which degrade ECM
2. Serine proteases:
2 ways to stop ECM degradation
1. Tissue inhibitors of metalloproteinases (TIMP1, 2, 3, 4) → ireversible
2. Serine protease inhibitors
Polypeptide chains found in collagen are high in?
Specific for 1 ECM component
Requires zinc or calcium
Cleave protein sequences at serine residues → work with metalloproteinases
Fibronectin's role in cancer
Carcinomas are unable to synthesize fibronectins → cell detaches from ECM
Type I collagen is found where?
Collagen cross linking with aged animals
Can become abnormal → loss of joint function
2 forms of hyaluronate
Proteoglycan (backbone in cartilage) or free molecule
Basal lamina surrounds what types of cells?
3. Schwann cells