961
By contrast , all proteins initiated with a methionine placed one residue upstream of the natural N terminus of PR failed to show specific proteolysis .
 GENE: PR
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
 Entities: PR 
Answer:
 GENE: PR