BIO130H1 Study Guide - Autophagy, Autophagosome, Mitochondrion

Which compartments are involved in vesicular transport? How are transport vesicles formed and targeted appropriately? What proteins are involved and what are their roles? What kinds of modifications are added to proteins in the ER? What determines whether a protein stays in the ER or moves on? Be sure to understand how vesicles fuse with their target membranes, and the consequences of fusion for the vesicle’s cargo as well as the proteins and lipids that are in the membrane. Know the structure of the Golgi apparatus and its role in intracellular trafficking. Understand the secretory process, endocytosis, exocytosis, function of the endosomes, and function of the lysosomes. Understand why endocytosis happens and how it can be regulated to take up specific molecules.

1) how does the timing and location of Arf1-GTP hydrolysis contribute the transport of COPI coated vesicles?

2) Consider cargo proteins that are destined for secretion to the extracellular space. For each of the following pairs of mutations or conditions, predict where the cargo will end up (ex. in the cytoplasm, a specific organelle, transport vesicles, multiple places, extracellular space) for: (i) & (ii) Each individual condition; & (iii) The combination of both.

A.(i) Normal Sar1 is mutated so that it hydrolyzes GTP immediately after binding GTP.

(ii)The signal recognition particle is mutated to be unable to bind to the SRP receptor.

(iii)Both

B.(i) A mitochondrial signal sequence is added to the C-terminus of the cargo protein.

(ii)v-SNAREs on COPII coated vesicles are mutated to be unable to bind t-SNAREs

(iii)Both

C. (i) COPII coat proteins are mutated so they don’t bind to the ER membrane.

(ii)COPI coat proteins are mutated so they don’t bind to the Golgi membrane.

(iii)Both

D.(i) Normal Sar1 is mutated so it binds tightly to GDP and cannot exchange it for GTP. (This leads to Sar1*-GDP being the only form of the protein in the cell.)

(ii) A transmembrane domain is added to the cargo protein.

(iii)Both

Consider cargo proteins that are destined for secretion to the extracellular space.

For each of the following pairs of mutations or conditions, predict where the cargo

will end up (ex. in the cytoplasm, a specific organelle, transport vesicles, multiple

places, extracellular space) for: (i) & (ii) Each individual condition; & (iii) The

combination of both.

(i) A mitochondrial signal sequence is added to the C-terminus of the cargo protein.

(ii) v-SNAREs on COPII coated vesicles are mutated to be unable to bind t-SNAREs

(iii) Both