"Fluorescence and Raman Measurements of Cell Membrane Receptor Clustering and Diffusion"
We are measuring the complex, dynamic organization and movement of cell membrane receptors. Our goal is to elucidate the role of extracellular, membrane & intracellular proteins and small molecules in altering integrin clustering and diffusion. Integrins are ubiquitous membrane proteins involved in cell signaling into and out of the cell. Noninvasive fluorescence resonance energy transfer measurements that do not require attaching fluorescent tags to the receptor are used to measure changes in integrin clustering. Fluorescence recovery after photobleaching (FRAP) records integrin diffusion, and FRAP is complemented with single particle tracking experiments to identify heterogeneous receptor diffusion. Our measurements provide vital information about the molecular mechanism of membrane organization and dynamics, which are important to cellular function. Finally, a scanning angle total internal reflection (SA-TIR) Raman microscope has been developed to tune the depth over which Raman spectra are collected to study interfacial phenomena with chemical specificity. Thirty nanometer axial resolution perpendicular to the focal plane has been measured, which is a significant improvement over confocal Raman measurements. Noninvasive and nondestructive SA-TIR Raman measurements of polymer and biopolymer films will be discussed.