10115
Because potassium is the most abundant intracellular cation , we propose that these are potassium - binding sites , but the specific structural and / or functional roles of the cation bound to these different sites remain to be investigated .
 Chemical: potassium; Chemical: potassium
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: potassium; Chemical: potassium