6244
Interactions between apo - CaM and the Kv7 . 4 tail involve two C - terminal tail segments , known as the A and B segments , whereas the interaction between Ca ( 2 + ) / CaM and the Kv7 . 4 C - terminal tail requires only the B segment .
 C, Ca ( 2 + ), C
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 C, Ca ( 2 + ), C