A long-standing but yet unattained objective in structural biology is to elucidate the physico-chemical basis of the molecular recognition. The key focus of my research is to understand the role of conformation and ultrafast dynamics of the individual biomolecules on different type of biomolecular recognitions like protein-ligand interactions, Protein-DNA interaction. Presently, my main research aim is to study the G-protein coupled receptors (GPCRs) dynamics during receptor-ligand interactions. GPCRs embedded in the plasma membrane of cells are proteins that mediate biological signals between the extra- and intracellular space. A vast number of marketed drugs bind to GPCRs, modifying their intracellular signaling profile. Upon binding of ligands from the extracellular space GPCRs undergo crucial conformational changes that allow them to recruit heterotrimeric G proteins (alpha, beta and gama subunits), arrestins and other signaling proteins. Thus understanding the complex conformational dynamics underlying the signal transduction via GPCRs through the cell membrane is a crucial and a longstanding challenge. Several biophysical approaches including fluorescence spectroscopy, X-ray crystallography, electron microscopy and many others stepped in to elucidate these important dynamical changes. Using fluorescence techniques like time correlated single photon counting or time resolved anisotropy, Forster resonance energy transfer and fluorescence correlation spectroscopy along with some high-end light microscopic technique it is possible to investigate the conformational dynamics and to find out the mechanism of downstream signaling processes.