In a neuron experiencing tau protein aggregation linked to neurodegenerative disease, which mechanism explains why the ubiquitin-proteasome system's (UPS) degradation rate slows despite increased ubiquitination?

💡 Explanation

The UPS slows because the misfolded, aggregated tau protein's sheer size and complex structure cause steric hindrance, physically blocking the proteasome's active sites, therefore preventing efficient protein binding and degradation, rather than ATP reversal, chaperone enhancement, or pH-related issues.

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