Which of the following posttranslational modifications are removed once a protein arrives at its final destination?

• A. Phosphorylation
• B. Ubiquitination
• C. Signal Sequences
• D. Protein Cleavage

Answer: (C)

Verified step by step guidance

1. Understand that posttranslational modifications are changes made to proteins after they are synthesized. These modifications can affect the protein's function, location, or stability.
2. Recognize that signal sequences are short peptides that direct the transport of a protein to its correct location within the cell. Once the protein reaches its destination, these sequences are often removed.
3. Phosphorylation involves the addition of a phosphate group to a protein, which can alter the protein's activity or function. This modification is typically reversible and not necessarily removed upon reaching the final destination.
4. Ubiquitination involves attaching ubiquitin molecules to a protein, often marking it for degradation. This modification is not typically removed once the protein reaches its destination.
5. Protein cleavage refers to the cutting of peptide bonds within a protein, which can activate or deactivate the protein. Signal sequences are often cleaved off once the protein reaches its final destination, making this a key posttranslational modification that is removed.