Q: In this task, you are given a sentence. You are expected to recognize the name of gene or protein. Although there might be several correct answers, you need to write one of them.
Scatchard ' s analysis of [ 3H ] - moxestrol ( R2858 ) and [ 3H ] - estradiol binding proves the existence of a single class of receptor sites having a dissociation constant of 0 . 18 - 2 . 4 X 10 ( - 9 ) M .
A:
receptor sites