SUMMARY (Core D) The multidisciplinary approaches proposed in this Program Project, whether structural or functional, depend on the availability of high quality and standardized biological samples and reagents. The overarching goal of the Apo/Lipoprotein and Production Core (Core D) is to meet this critical need across the entire Program. The Core is designed to provide the following services: 1) Isolation, characterization, and distribution of lipoproteins and apolipoproteins isolated from human plasma, 2) Expression, purification, and distribution of recombinant apolipoproteins, isotopically labeled proteins, and peptide mass spectrometry standards, 3) Design, expression, purification, and distribution of customized apolipoprotein mutants, including new constructs for assessing the mobility of HDL-bound proteins, 4) Generation, characterization, and distribution of reconstituted HDL particles customized to test specific hypotheses from around the Program, and 5) Generation and characterization of targeted nanobody reagents for cryo-EM studies. Core D will be led by W. Sean Davidson, Ph.D., working with two outstanding and highly experienced research technicians, Jamie Morris and Scott Street. It will be located at the University of Cincinnati, which has extensive and documented experience in all of the Core’s proposed services. In the previous PPG cycle, Core D filled over 550 orders from the other Projects and Cores, not including hundreds more that were used in the Davidson lab. Based on prices charged by traditional biochemical supply sources, the retail value of these samples far exceeds the resources needed to run the core. Thus, this resource contributes substantially to the synergy and cost-effectiveness of the Program’s ongoing work. We believe that few, if any, facilities in the world can provide these services in a single place.