According to the “Hawaiian Punch” principle, different compartments of the secretory and endocytic pathways are topologically equivalent to each other and to the extracellular space. Explain how vesicular transport generates this topological equivalence.

As we learned when studying protein trafficking, proteins need a nuclear localization signal in order to move from the cytosol into the nucleus via the nuclear pore complex. Protein A contains a typical nuclear localization signal but surprisingly is usually found in the cytosol. When the cell is exposed to a certain hormone, protein A moves from the cytosol into the nucleus, where it turns on genes involved in cell division.When you purify protein A from cells that have not been treated with the hormone, you find that protein B is always complexed with it. To determine the function of protein B, you engineer cells lacking the gene for protein B. You compare normal and gene B deletion cells by separating and isolating the proteins found in the cytoplasm and those found in the nucleus. You then run these proteins on a protein electrophoresis gel to separate them by size. You identify the presence of protein A and protein B by looking for their characteristic bands on the gel (which is…

Using the experimental results, describe the pathway that secretary proteins take from their synthesis to their release from the cell.

The amino acid sequence Leu-His-Arg-Leu-Asp-Ala-Gln-SerLys-Leu-Ser-Ser is a signal sequence that directs proteinstowards the endoplasmic reticulum, say if it is true or false if it is false justify it.

If cells are treated with colchicine, a drug that promotes microtubule disassembly, the location of the ER and Golgi both change dramatically.  Rather than being spread out quite widely through the cytoplasm, the ER appears to collapse into the area near the nucleus. (Recall that the ER membrane and the outer nuclear envelope are continuous with one another). In contrast, the Golgi stacks disperse from their usually more compact, central location to areas all over the cell. However, if colchicine is removed, and microtubules are allowed to reassemble, both organelles eventually return to their normal distribution in the cells. How do you account for the change in distribution of the ER & Golgi when microtubules are depolymerized? What protein(s), other than tubulins, allow normal cellular organization to be restored once colchicine is removed? (answer should include information to explain both the ER & Golgi)

4. i)List two reasons why membrane fusion is energy demanding. ii) List the three SNARE proteins which catalyze fusion of vesicle with target membranes and specify their localizations. iii) Briefly describe the structures of SNARE proteins and SNARE complex. iv) What does botulism neurotoxins do to SNARE proteins? How do these toxins lead to muscle paralysis? 5. How does the structure of the potassium channel promote specific binding of potassium?

Is the movement of sodium through SGlut-1 during co-transport simple diffusion, facilitated diffusion, active transport, or secondary active transport? And is the movement of glucose through SGlut-1 during co-transport simple diffusion, facilitated diffusion, primary active transport, or secondary active transport?

Demonstrate the listed processes

List and describe the three main types of cytoskeleton. If you wanted to do immunocytochemistry to specifically stain each type of cytoskeleton, what is a protein that could be used for each cytoskeletal type (in other words, what is a unique protein for each cytoskeletal type)? What are three types of actin structures? Describe the involvement of actin structures in cell migration. How is the growth and shrinking of microtubules regulated? Then describe the roles of microtubules in: chromosomal separation during mitosis and the movement of organelles and vesicles within a cell. Describe a possible mechanism on how signaling pathways might impact the cytoskeleton, so that cell migration could be regulated in a localized manner within a multicellular organism. (hint: think about the possible transcriptional regulation of the G-protein regulators) What are 2 main challenges of protein targeting? Then describe one way these challenges are overcome during signal-based targeting and one way…

1- Vesicular transport occurs through budding of clathrin-coated vesicles from eucaryotic plasma membrane through various types of proteins including adaptins, clathrin, and dynamin-GTP which are added to the membrane preparation. What would happenes if these are mutated or omitted (A) adaptins? (B) clathrin? (C) dynamin? (D) What would you observe if the plasma membrane were from bacteria? coated vesicle clathrin coat UNCOATING VESICLE FORMATION adaptin cargo receptor -adaptin naked transport vesicle dynamin CYTOSOL EXTRACELLULAR SPACE cargo molecules