859
The two yeast pheromone receptors , the a and alpha - factor receptors , share many functional similarities : both G protein - coupled receptors couple to the same downstream signal transduction pathway , and both receptors undergo feedback regulation involving increased phosphorylation on their C - terminal domains in response to ligand challenge .
 GENE: yeast pheromone receptors; GENE: a and alpha - factor receptors; GENE: G protein - coupled receptors
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
 GENE: yeast pheromone receptors; GENE: a and alpha - factor receptors; GENE: G protein - coupled receptors