UC San Diego

Cell membranes are a crucial component to the life of a cell. The membrane defines boundaries, provides structural elements, and contains proteins that serve as sensor receptors to transmit external cues across the phospholipid bilayer, either from the environment to the cell's interior or from the cytosol to a particular sub- cellular compartment. One type of proteins found spanning these lipid bilayers are known as the integral membrane proteins (IMPs). Since the dysfunction of this class of proteins has been associated with multiple disease states, a large initiative has developed to target them for new pharmaceutical therapeutics. Unfortunately, many obstacles have slowed the progression of IMP research. Some of these deterrents include low IMP over-expression levels, detergent selection, and detergent extraction. The drawbacks to studying IMPs can account for the small percentage of IMP structures that have been deposited in the PDB. Here I describe the structural and functional studies of multiple receptors from different classes. The first study includes analysis of the chemokine CCL14 and the G protein-coupled receptor CCR5 and provides new information for the potential to use chemokines in CCR5 receptor targeted HIV-1 therapeutics. Other studies presented here include the structure determination of hIMP3, the NH₂-terminal domain of a glutamate receptor, and an adenoviral protein and can aid in the development of drugs related to human neurological diseases and cancer. To speed the progression of IMP studies, there is a current need for the improvement of existing methods and for the creation of new ones. Previous studies have been compiled here to summarize the creation of histidine kinase receptor chimeras and the benefits of engineering new receptor signal transduction circuits. Moreover, I discuss the Mistic-fusion system for use in boosting IMP expression levels while maintaining functionality of the fused receptor EnvZ. Lastly, I illustrate that by combining cell-free expression, the CDL-strategy, and the use of fast NMR analysis, the structure of hIMP3 was solved within a few months. By using new techniques and determining the structures of IMPs and their signaling partners, we can gain a better understanding of the molecular mechanisms behind receptor signaling