Consider cargo proteins that are destined for secretion to the extracellular spa
ID: 163255 • Letter: C
Question
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) 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
Explanation / Answer
Answer
The Sar 1 gene controls coat assembles and which promote the formation transport vesicles from endoplasmic reticulum. The coats have two important functions which are, the formation of cargo vesicle from ER membrane and selection of the cargo. If sar1 is mutated, it tightly binds to GDP and can’t exchange GTP. Thus, cargo unable to load up or not transported from starting point to final destination.
Finally, cargo will end up in the cell cytoplasm or cell organelles or transport vesicles are unable to unload.