How does ubiquitination affect enzyme activity and cellular protein concentration?

• A. Ubiquitination increases enzyme activity by stabilizing proteins.
• B. Ubiquitination increases protein concentration by promoting protein synthesis.
• C. Ubiquitination decreases enzyme activity by marking proteins for degradation, thus reducing cellular protein concentration.
• D. Ubiquitination has no effect on enzyme activity or protein concentration.

Answer: (C)