22_ECM Flashcards
What is the function of the glycocalyx? What is it composed of?
Composed of carbohydrate projections extending from integral membrane proteins.
Functions:
- cell-cell/ cell-substratum interactions
- mechanical protection/ barrier
What is present in the EC space between intestinal villi to provide mechanical space?
Glycocalyx
What is the innermost layer of the EC space?
Glycocalyx
Chondrocytes have a (large/small) ECM.
large
How many subunits does an integrin possess?
two (alpha & beta)
Integrin involvement in cell survival signalling is an example of (outside-in/inside-out) signalling.
outside-in
Activation and extension of integrins in neutrophil trapping in an example of (inside-out/outside-in) signalling.
inside-in
PAF–> GPCR on neutrophil –> neutrophil activation
What is talin? What protein does it activate?
talin indirectly links integrins to the actin cytoskeleton
It is involved in activation of integrins
What peptide sequence is present in many integrin substrates? What are some examples of proteins that possess this sequence?
RGD sequence
proteoglycans, fibronectin, laminin, collagen, etc.
Which glycoprotein is present solely in the ECM?
collagen
What are some cells that produce collagen?
fibroblasts in dermis, epithelial cells, smooth muscle cells
Describe the protein structure of collagen. (2˙ structure elements, #of subunits)
3 alpha chains
How are the layers of collagen in the corneal stroma arranged?
uniform alternating layers to provide strength and maintain transparency
In proteoglycans, core proteins carry (covalently/ionically) attached GAGs, which have a (-/+/neutral) charge.
covalently
negative
How do proteoglycans form a porous, hydrated gel? What is the benefit of this gel?
by binding large numbers of cations and water molecules
Resistance to crushing/compression
Which proteins provide a scaffold for proteoglycans in the ECM?
collagens
In a proteoglycan complex, what molecules make up the central core?
hyaluronic acid
Fibronectins are composed of 2 proteins; how are they joined?
disulfide bridges
What role do fibronectins play during embryogenesis?
provide pathways for migrating cells
Why do cells die when they move off fibronectin?
integrins can’t bind their appropriate substrate; there is no survival signal; cells die.
Which ECM is a cross-shaped trimer joined by disulfide bonds?
laminin
Which two ECM proteins act as pathways/guides for migration?
fibronectin & laminin
Which dimeric ECM protein is highly interactive and has many binding sites for other ECM proteins?
Fibronectin
Which EMC proteins are trimers?
collagen & Laminin
