This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Which of the functions are TRUE regarding C-terminal domain of androgen receptor protein? 
Select and explain. 
A. Ligand binding, B. Increasing biological half life, C. Increasing the affinity of receptor to DNA, D. Increasing the level of transcription
A: Ligand binding
Answer: A: Ligand binding 
Explanation: The androgen receptor proteins contain 3 common domains: 1- Highly conserved central domain that is responsible for DNA binding 2- N-terminal region that is involved in trascriptional activation, and 3- C-terminal domain that binds ligand Ref: Harper's Illustrated Biochemistry 27th Edition, Page 477; Molecular cell biology, December 19 (12); 8383 - 8392; Urotext Basics By R. A. S. Hemat, Edition 2003, Page 68.