Consider cargo proteins that are destined for secretion to the extracellular spa
ID: 163253 • 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) 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
Explanation / Answer
The signal sequence should be present at the N terminus protein for targetting the protein to specific compartment. For retension of protein in specific compartment, the signal sequence is present at C terminus.
If the mitochondrial signal is at the C terminus of the cargo protein than the protein will be held in the Mitochondria only and not transported.
SNARE proteins mediate vesicle fusion thus transporting the targets to the membranes. It is of two categories: vesicle or v-SNAREs and target or t-SNAREs. v-SNARE are present in the membrane of transport vesicles during budding. t-SNARE guide the v-SNARE and form the SNARE complex. If the v-SNARE donot bind to the v-SNARE than the complex is not formed.