Motion analysis of receptors and ligands in high resolution fluorescence microscopy images

Monitoring the dynamical behavior of receptors and ligands via single-molecule fluorescence microscopy allows quantifying the interactions between these two subcellular structures at a very high spatial and temporal resolution. We have developed a probabilistic approach to determine the positions of receptors and ligands over time in two-channel image sequences of small protein complexes and single molecules as well as to estimate the transient motion behaviors of individual structures based on hybrid particle filters. We have applied the approach to synthetic data and to real fluorescence microscopy data of the erythropoietin receptor (EpoR) and its ligand erythropoietin (Epo) and quantified the performance. Our approach allows accurately analyzing the motion of the subcellular structures as well as correlating their motion with the interactions between the structures under different experimental conditions.