6174
Previous studies indicated that the 20S proteasome is a catalytic core of the 26S proteolytic complex that possesses a latent multicatalytic proteinase activity and catalyzes an ATP - dependent , selective breakdown of proteins ligated to ubiquitin .
 20S proteasome, 26S proteolytic complex, ubiquitin
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 20S proteasome, 26S proteolytic complex, ubiquitin