A protein with a mutated ER retention signal is found in the Golgi apparatus. What is the most likely reason for this mislocalization?

• A. The protein lacked a start transfer sequence, preventing its insertion into the ER membrane.
• B. The protein was misfolded and degraded by ERAD proteins.
• C. The protein was glycosylated incorrectly, leading to its transport to the Golgi.
• D. The mutated retention signal failed to retain the protein in the ER, allowing it to be transported to the Golgi.

Answer: (D)