? Many cancer-implicated proteins are integral membrane proteins (IMPs). There is a pressing need for improved methods for the production of IMP constructs for use in high-resolution structure determination efforts. Three years ago, we completed a fifteen- year effort to develop methods for the performance of peptide amide hydrogen/deuterium exchange- mass spectrometry (DXMS). In collaboration with the Joint Center for Structural Genomics (JCSG), we recently demonstrated that DXMS can provide precisely the information needed to guide the design of well-crystallizing constructs of otherwise poorly-crystallizing soluble proteins. The NCI IMAT program is now funding our efforts to optimize DXMS-guided construct design for soluble cancer-implicated proteins (R33 CA099835). Until recently, we thought it unlikely that successful DXMS analysis of membrane proteins would be possible, and this funded grant contains no reference to membrane proteins (IMPs), nor does it support work on them. However, insights and preliminary studies described in the present application now make it likely that, with intensive development work, we can devise highly modified methods that will allow the facile DXMS analysis of IMPs. Development of membrane protein DXMS will greatly impact the structural biology of cancerimplicated IMPs, which are particularly difficult to prepare in crystallizable form. Initial year 1 development efforts will focus on the integrin allbbS, with which I have had considerable experience. Integrins are widely implicated in cancer cell and cancer vasculature biology, and findings with the prototypic allbbS integrin have proven applicable to the understanding of all integrins. The resulting IMPDXMS methods will be further refined and validated in year 2 through study of additional cancer- relevant IMPs and daughter constructs provided by Dr. Raymond Stevens, P.I. of the newly NIH-funded JCSG Center for Innovative Membrane Protein Technologies (JCIMPT). Once IMP- DXMS has been fully developed and validated, it will be made available to investigators studying cancer-implicated IMPs, by integrating the methods with our soluble-protein DXMS resource now supported by the NCI IMAT program. Thus the NCI's investment in presently funded DXMS work will be greatly leveraged by the relatively modest support requested for the development of IMP-DXMS. ? ?
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