9420174 Fasman Membrane proteins, such as receptors, ion channels, transport channels, hormone receptors, etc. represent an important class of proteins. Understanding their structure would reveal important aspects of their functional role. However, crystallization of membrane proteins has proven to be difficult and this has raised major stumbling blocks to obtaining their three-dimensional structure. To date, the structures of only a few membrane proteins have been determined by X-ray diffraction studies or by electron microscopy. The proposed studies are to further develop a new approach for the crystallization of membrane proteins by making them water soluble by conjugation to methoxypolyethylene glycol (mPEG), a water soluble polymer. These conjugates have already been formed with two membrane proteins, bacteriorhodopsin and porin and have been found capable of refolding to their native structures. Preliminary experiments have shown that one of these conjugates, mPEG porin, can be crystallized, but the crystals are as yet too small for X-ray diffraction studies. Research is proposed to further develop the method to a point where useful crystals can be obtained routinely and to carry out X-ray diffraction studies with one or more of these protein conjugates. ***
