11552
( 1997 ) Nature 387 , 370 - 376 ) ] , we suggest that the metal fluoride ions replaced phosphate at the two ATP - binding sites of the iron protein , Kp2 .
 Kp2
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 Kp2