Marine pollution is of concern for human health through our exposure to contaminated food from the sea. What remains poorly understood is why some chemicals are persistent, accumulating in marine organisms and then in humans, while others are not. Multidrug resistance (MDR) transporters, belonging to the ATP Binding Cassette (ABC) family, are major biological determinants of intracellular chemical accumulation. While they have been implicated as determinants of environmental chemical persistence and used as tools for predicting availability and efficacy of drugs, they have yet to be systematically applied to predicting persistence of pollutants. The investigators' preliminary data indicate striking functional conservation of the major sub-family types (ABCB, ABCC and ABCG) of xenobiotic eliminating transporters between sea urchins and man. This application explores the molecular basis for this conserved substrate selectivity as a first step towards application of transporter biology to prediction of pollutant persistence. In this project, the investigators will over-express, solubilize, and purify sea urchin multidrug efflux transporter proteins, develop assays for their interaction with major marine pollutants and attempt to determine their high-resolution structures. They will measure their interaction with persistent marine pollutants using anisotropy, ATPase and whole cell assays. By comparing structure and functions of sea urchin with those of mammalian transporter proteins, already available through the TransportPDB pipeline, they will identify conserved residues and structural features that are essential for predicting substrate interaction in the poly-specific binding pocket of these ABC transporters