Study Question Sets for Exam 3
Study Question Set 19 -- Cytoskeleton & Actin - Part 2

1. Describe the anchoring of the core microfilaments of brush border microvilli to the plasma membrane at the apical end of enterocytes.
2. Suggest a role for myosin I in brush border microvilli.
3. Indicate the major proteins binding the core MFs in the brush border microvilli of an enterocyte.
4. What actin filament organization would one expect to see in a region of a cell where one finds each of the following? Explain.
1. fimbrin
2. filamin
3. alpha actinin
5. In what way do myosin V and VI provide for differences in movements of vesicles in a cell? Explain.
6. Cell migration:
1. What are the roles of pseudopodia, lamellipodia, or filopodia in migration of cells such as fibroblasts?
2. Explain how the degree of branching of actin filaments can determine whether a surface extension on a migrating cell is a filopodium or a lamellipoodium.
3. Cite briefly experimental evidence that demonstrates the importance of functional filamin in the formation of lamellipodia.
4. Why is phosphorylation of the regulatory light chain of myosin II in non-muscle cells essential to the fromation of focal adhesions (= focal contacts)?


5. Describe the relationship between stress fibers and focal contacts.
6. Describe the importance of stress fibers and focal contacts to cell migration.
7. What is responsible for advancing the bulk of the cell cytoplasm during typical migration of a fibroblast?
8. What is the significance of the fact that the integrins of focal contacts bind to fibronectin?

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