What is the primary mechanism by which the ubiquitin-proteasome pathway regulates protein degradation in cells?

A Tagging proteins with ubiquitin for degradation by lysosomes
B Marking proteins with ubiquitin for degradation by proteasomes ✓
C Synthesizing proteins with ubiquitin for secretion
D Transporting proteins with ubiquitin into mitochondria

Explanation

The ubiquitin-proteasome pathway is a key regulatory mechanism for protein degradation, where proteins are tagged with ubiquitin and then degraded by proteasomes.

Source

Alberts et al., Molecular Biology of the Cell
Protein Metabolism Biochemistry Protein Degradation Medium NURSING Confidence: high