ECM 1.16-1.18 Flashcards
The ECM is the defining feature of what tissue type?
Connective tissue
What are GAGs?
Heteropolymer chains containing repeating disaccharide units of an amino sugar and uronic acid.
What are two examples of amino sugars? Examples of uronic acid?
N-acetylglucosamine, N-acetylgalactosamine.
Glucaronic and Iduronic acid
What are the major structural polysaccharides of ECM, CT, and Outer cell membrane surfaces?
GAGs
Why are GAGs highly negatively charged and easily attract water?
Because they contain sulfate and carboxyl groups
What does the accumulation of various GAGs (due to enzyme deficiencies) result in?
Several syndromic diseases such as Hunter’s and Hurler’s diseases.
Which two GAGs most frequently accumulate two cause mucopolysaccharide storage diseases?
Heparan sulfate and Dermatan sulfate
What is the most abundant GAG?
Chondroitin sulfate
Which GAG does not form a proteoglycan and does not contain sulfur?
Hyaluronic Acid
Which GAG is found in basement membranes?
Heparan sulfate
Which GAG is highly sulfated and acts as an anticoagulant?
Heparin
What are Proteoglycans (PGs)?
Complex carbs that have a central protein molecule to which many GAGs are attached in a radial (brushlike) pattern.
Which trisaccharide is involved in the linkage of GAGs to the central protein of a PG?
2 galactose + 1 xylose (if glucuronic acid is accounted for then it may be considered tetrasaccharide)
What is the central protein of a PG rich in?
serine and threonine
Where are PGs located mostly?
in the ECM
What are PG Aggregates?
PGs joined to a long hyaluronate molecule (not a protein core, though looks like it)
Which GAG acts as a biological shock absorber and can be found in synovial fluid and vitreous fluid?
Hyaluronic acid, which does not form a PG, but has many PGs linked to it to form an aggregate
What are the three classes of PGs?
Small leucine-rich proteoglycans (SLRPs).
Modular proteoglycans
Cell-surface proteoglycans
What is required for PG degradation?
3 exoglycosidases
4 sulfatases
1 acetyl transferase
Removal of monosaccharides
What is it about the conformation of PG that makes it susceptible to extracellular proteases?
Its linear conformation
What is the form and function of the four extracellular matrix proteins?
Structure is achieved by collagen and elastin.
Adhesion is achieved by fibronectin and laminin
What are the major functions of collagen?
Provides tensile strength, regulates cell adhesion, support chemotaxis and migration and directs tissue development.
Which cells synthesize and secrete collagen?
Fibroblasts
How are fibroblasts able to organize collagen fibrils into sheets and cables?
By exerting tension of matrix
What are collagen proteins rich in?
Glycine, Proline, Hydroxyproline and Hydroxylysine
