Liu Zhi-Jie group current research is focused on the study of human G protein coupled receptors (GPCR) and related cell signal transductions. GPCRs constitute the largest protein family in human body, they are responsible for about 80% of the cell surface signal transductions, play important roles in many physiological activities and related to many diseases. More than 30% of marketed drugs target GPCRs. However, GPCRs are only responsible for the initial step of cell surface signal transductions, there are more than 200 downstream signaling pathways participated in the cell functional modulations which we know very little about. The long term research focus will be shifted from GPCR structural biology to GPCR mediated signaling transduction mechanism in neuron cells by integrating different imaging and functional analysis methods. Our special interest is GPCR biased signaling which is important for developing effective and side effect free drugs.