Dissecting cell transduction
Receptors that are coupled to G proteins (GPCRs) constitute one of the most important classes of cell surface receptors. They mediate diverse cellular processes in response to hormones, peptides or light. Given their central role, a large number of drugs in the market have been designed to target these receptors. Although there is a great deal of structural information on GPCRs, the mechanistic details of the downstream transduction events remain elusive. Scientists on the EU-funded SIGT-OR-G (Signal transduction of olfactory receptors to their G protein) project focused on the interaction of olfactory receptors (OR) and its G proteins to address this lack of knowledge. Considerable efforts went into the optimisation of all the important steps implicated in the functional expression and purification of ORs and the G protein. To facilitate their studies, researchers first expressed human OR5P3 in cells and then directly observed the specific binding of a fluorescent odorant. To investigate the interaction between the OR and its G protein, they synthesised a fluorescent peptide predicted to be directly involved in the OR-G complex. SIGT-OR-G also tested another approach that involved the isolation of ORs together with the entire signalling machinery in vesicles. For this purpose, they developed a procedure for purification and characterisation of such cell-derived vesicles. Collectively, the methods and tools developed during the SIGT-OR-G will aid the future investigation of ORs and other transmembrane receptors. In the long term the generated information could prove useful in the design of novel pharmaceuticals.
Keywords
Cell transduction, receptor, signalling, G protein, drug, olfactory
