594
The predicted receptor structure includes a cysteine - rich extracellular domain , a single hydrophobic transmembrane domain , and a predicted cytoplasmic serine / threonine kinase domain .
 cytoplasmic serine / threonine kinase domain
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 cytoplasmic serine / threonine kinase domain