While studying the secretory pathway, you make the following observation about proteins destined for the ER: Proteins translated in vitro in the absence of microsomes migrate more slowly on an SDS PAGE gel than those translated in the presence of microsomes. What might account for the observed protein size difference? A. SRP, present only in microsomes, and binds to and removes the signal sequence from the protein, resulting in a protein is smaller and migrates more quickly on a gel. B. Signal peptidase, present only in the microsomes, cleaves the signal sequence from the protein, making the protein smaller and therefore migrate more quickly. C. In vitro translated proteins tend to be larger due to a more stable poly A tail D. Signal peptidase, present only in the microsomes, adds a signal sequence to the protein, making the protein larger and therefore migrate more slowly.
While studying the secretory pathway, you make the following observation about proteins destined for the ER:
Proteins translated in vitro in the absence of microsomes migrate more slowly on an SDS PAGE gel than those translated in the presence of microsomes.
What might account for the observed protein size difference?
| A. |
SRP, present only in microsomes, and binds to and removes the signal sequence from the protein, resulting in a protein is smaller and migrates more quickly on a gel.
|
|
| B. |
Signal peptidase, present only in the microsomes, cleaves the signal sequence from the protein, making the protein smaller and therefore migrate more quickly.
|
|
| C. |
In vitro translated proteins tend to be larger due to a more stable poly A tail
|
|
| D. |
Signal peptidase, present only in the microsomes, adds a signal sequence to the protein, making the protein larger and therefore migrate more slowly. |
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