Structural Mapping of Membrane-Associated Proteins: A Case Study of The IgE-Receptor Complex
Elucidation of the structure and function of membrane-associated proteins has emerged as one of the major new challenges in protein chemistry. Fluorescence allows quantitative measurements to be made on receptor samples at typical nanomolar concentrations, and resonance energy transfer from fluorescent donors to acceptor chromophores can be measured and used as a “ruler” to determine distances between these probes located specifically on the macromolecule. The amphipathic probes have spectral properties such that some can act as resonance energy transfer donors to others acting as acceptors, and, therefore, energy transfer measurements can be used to monitor the presence of these probes in the membrane and their spatial arrangement. The immunoglobulin E receptor system on rat basophilic leukemia cells has proven to be amenable to detailed structural mapping by energy transfer measurements using a variety of probes and experimental approaches.