Bonus question: When integrin-ECM adhesion is lost, cells die via detachment-induced apoptosis. If you culture isolated liver cells (hepatocytes) and add RGD peptides, would you expect them to survive? Why or why not? Explain your answer (5 points)

Epidermolysis bullosa is a group of rare medical conditions that cause fragile, blistering skin. Patients with the disease have genetic alterations in one or multiple proteins involved in the formation of the adhesive structures called hemidesomosomes. These include: (select all that apply)

Integrins act as a bridge between ECM components, the cytoskeleton, and other proteins, and regulate many cell functions. A. Indicate how the peptide of this protein would look like. Indicate what signals (if any) the newly synthesized protein should have to efficiently reach its final destination and where they would be located in the peptide (3 points)     B. What type of ribosomes will fully synthesize this protein? (2 points) C. What type of vesicles (protein-coated vesicles) would transport this protein?  (2 points)

Vesicular transport across the endomembrane system can occur in coated vesicles covered by: (select all that apply)

SLE (Lupus) involves an autoimmune-induced inflammation. Joint pain is the most common symptom and results from inflammation around the joint. The inflammatory process can increase proteolytic activity (breakdown of proteins)  in the ECM. In a specific case of SLE, lab tests suggest that water retention drops dramatically in cartilages. This can result in joint damage and pain. A. Based on this information, degradation of which protein will be most affected in SLE? (2 points) B. Which of the following hydropathy plots will better represent the affected protein? Briefly explain your answer (4 points)

In one experiment, you coat a petri dish with fibronectin and proteoglycan and culture cells on a petri dish. Cells adhere to the dish. In another set of experiments (Experiments 1-4), you repeat the previous procedure but this time add one synthetic peptide to each of the culture dishes as the cells are added. A. What are the outcomes of experiments 1 to 4? Hint: do cells adhere or not in each experiment? (4 points) B. Explain how you determined if cells adhered or not in experiments 1 to 4 (4 points)  

Autoradiography is a technique that allows to track the incorporation of radiolabeled compounds.  In which part(s) of the cell would you expect radiolabeled Leucine to be incorporated?

Bonus question: You identify a new enzyme called “signalase” that removes the signal peptide of any protein that contains it. You expose the following proteins to the action of signalase. Which ones  would be affected by this treatment?  Select all that apply

According to the assigned reading, the ability to feel “lumps” during a breast exam is associated with

The unfolded protein response (UPR): Is triggered when there are too many misfolded proteins in the ER. Is inhibited by BiP molecules. Occurs in the cytoplasm Involves the synthesis of more chaperones in the ER. Inhibits enzymes involved in protein synthesis.