Question

What would happen if you change the hydrophobic amino acids in the ER signal sequence into charged amino acids.

a) The altered signal sequence will not be recognized and the protein will remain in the cytosol
b) the altered signal sequence will not be recognized and the protein will remain in the ER until a chaperone protein can modify the sequence to contain an ER signal
c)the altered signal sequence will cause the protein to be tagged with ubiquinone for for degradation
d)the altered sequence will immediately cause the cell to undergo apoptosis

Answer 1

Changing the hydrophobic amino acids in the ER signal sequence into charged amino acids can have different effects on the protein's fate. It may prevent recognition and result in the protein remaining in the cytosol, or it may require modification by chaperone proteins before being directed to the ER. Alternatively, the altered signal sequence may lead to protein degradation if misfolding or inappropriate localization occurs.

Step-by-step explanation:

Changing the hydrophobic amino acids in the ER signal sequence into charged amino acids can have different effects on the protein's fate:

1. The altered signal sequence will not be recognized and the protein will remain in the cytosol. The hydrophobic amino acids in the signal sequence are essential for its recognition by cellular factors responsible for transporting the protein to the endoplasmic reticulum (ER). Without these hydrophobic amino acids, the altered signal sequence will fail to be recognized, resulting in the protein remaining in the cytosol.
2. The altered signal sequence will not be recognized and the protein will remain in the ER until a chaperone protein can modify the sequence to contain an ER signal. The altered signal sequence may still be recognized by chaperone proteins that can modify it to contain an ER signal. In this case, the protein will be retained in the ER until the modification occurs and it can be properly directed to its destination.
3. The altered signal sequence will cause the protein to be tagged with ubiquitin for degradation. If the altered signal sequence is not recognized or modified, it may lead to misfolding or inappropriate localization of the protein. In such cases, the protein may be tagged with ubiquitin for degradation by the proteasome.
4. The altered sequence will not immediately cause the cell to undergo apoptosis. Apoptosis is a programmed cell death process that is typically triggered by specific cellular signals, such as DNA damage or certain developmental cues. A change in the signal sequence of a protein would not directly trigger apoptosis.