7033
Comparison of the deduced amino acid sequences with protein sequences of T . pyriformis H2As showed only two and three differences respectively , in a total of 137 amino acids for H2A1 , and 132 amino acids for H2A2 , indicating the two genes arose before the divergence of these two species .
 H2As, H2A1, H2A2
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 H2As, H2A1, H2A2