1189
Reconstitution of a cell-free system and identification of the ubiquitin-carrier protein , E2 , and a novel ubiquitin-protein ligase , E3 , involved in conjugation.
 protein: ubiquitin-carrier protein; protein: E2; protein: ubiquitin-protein ligase; protein: E3
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: cell line, protein, RNA, DNA, cell type 
Text: {0} 
Answer:
 protein: ubiquitin-carrier protein; protein: E2; protein: ubiquitin-protein ligase; protein: E3