Exam 4 (7)

Question 1

7 Steps of Collagen Fiber Synthesis

Answer 1

(1-5 in the ER/Golgi)
1. Pro-collagen alpha chain synthesized
2. Ascorbic Acid acts as catalyst for hydroxylation of selected prolines and lysines on (1)
3. Glycosylation of Selected Hydroxylysines
4. Self-assembly of 3 pro-alpha chains
5. Pro-collagen triple helix formation!!

6. Secreted to Extracellular Environment
7. Cleavage of Propeptides on the alpha helices
8. Self-assembly into fibrils (multiple triple helices in one structure)
9. Collagen fibrils aggregate to form collagen fibers!!

Question 2

Role of Proteoglycans in the ECM

Answer 2

Glycoproteins consisting of core protein and glycosaminoglycans (GAGs) –> form long linear polymers of repeating disaccharides
(can have joint lubricating quality)

Question 3

2 Roles of Integrins in Connective Structures

Answer 3

1. Links laminin to intermediate filaments @ hemidesmosomes
2. Mediate linkages of fibronectin to actin @ focal adhesions

Question 4

General Role of Fibronectin in the ECM

Answer 4

Long, flexible molecule that contains various binding domains for collagens, proteoglycans, adhesion receptors, and other EC signaling molecules

Question 5

3 Specific Roles of Fibronectin in ECM

Answer 5

1. Organizes components of the ECM
2. Regulates cell to matrix adhesion
3. Changes organization of Actin Cytoskeleton to influence shape and movement of cell

Question 6

Special Fibronectin Note (related to Integrins)

Answer 6

Fibronectin is known to bind to integrins when they contain a RGD sequence

Question 7

Defects in Cell Adhesion –> __?

Answer 7

Diseases and Cancers!