Most neurodegenerative diseases involve inability to remove misfolded/aggregated proteins. The cellular organelle that often fails in this context is:

a. mitochondria

b. nucleolus

c. proteasome

d. none of the above

Answer: c. proteasome

Explanation:

Proteasomes are extremely important multi-catalytic proteases and are involved in various cellular functions. The proteasome is an essential component of eukaryotic cells and is responsible for the ATP-dependent proteolytic degradation of most cellular proteins. They are present in the nucleus and cytosol and can represent up to 1% of total cell proteins. Proteasomes generally degrade proteins to small peptides, most of which are rapidly hydrolyzed by cytoplasmic exopeptidases. It catalyzes the rapid degradation of many enzymes, regulatory proteins, and eliminates abnormal proteins resulting from mutation or damaged proteins. The inability of this cellular organelle can lead to neurodegenerative diseases, such as Parkinson's disease.