1. College of Life Science; Zhejiang Sci-Tech University; Hangzhou 310018 China
2. Zhejiang Provincial Key Laboratory of Silkworm Bioreactor and Biomedicine; Hangzhou 310018 China
3. Laboratory of Structural Science; Center for Structural Biology and Drug Discovery, Van Andel Research Institute; Grand Rapids Michigan 49503 USA
4. VARI-SIMM Center for Structure and Function of Drug Targets and the CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Science; Shanghai 201203 China