Description of substrate specificity determinants in Solute Carrier Transporters

描述（由申请人提供）：溶质载体（SLC）超家族成员是膜转运蛋白，控制溶质的摄取和排出，包括必需的细胞化合物、环境毒素和跨生物膜的治疗药物。该提案的主要目的是通过对这一关键膜转运蛋白超家族的底物特异性提供全面的综合实验和计算描述，有助于我们理解个体对药物反应差异的遗传基础（药物遗传学）。本研究的第一个目标是在人类基因组中发现新的SLC超家族成员，并阐明SLC家族之间的关系；这将通过绘制区分一个家族与另一个家族的序列、结构和化学特征来实现。对相关蛋白进行分组将有助于根据未鉴定蛋白的鉴定同源物推断其结构和功能特征（例如，折叠、配体结合位点和分子机制）的相似性。该分类方案很可能为SLC转运体结构的建模提供信息，这是描述其底物特异性的先决条件。第二个目标是描述选定SLC家族中底物特异性的序列和结构决定因素。这一目标将通过将序列分析、结构比较、比较建模、配体对接和虚拟筛选等计算方法与实验相结合来实现。实验工作将与其他实验室合作进行；它将包括功能表征使用各种分析，包括配体摄取和动力学测量。第三个目标是利用SLC家族的特异性决定因素信息来开发遗传变异对转运蛋白功能影响的预测模型，这将在临床重要的底物上进行实验测试。最终，在这项研究中获得的结果将有助于我们理解为什么个体对同一种药物的反应不同。特别是，研究结果与临床观察到的疾病状态和个体对药物反应的变化之间的相关性可以成为个性化医疗的重要一步，大大有利于公共卫生。

DESCRIPTION (provided by applicant): Solute Carrier (SLC) superfamily members are membrane transporter proteins that control the uptake and efflux of solutes, including essential cellular compounds, environmental toxins and therapeutic drugs across biological membranes. The broad aim of this proposal is to contribute to our understanding of the genetic basis of variation among individuals' response to drugs (pharmacogenetics), by providing comprehensive integrated experimental and computational description of substrate specificity of this key membrane transporter superfamily. The first goal of this proposal is to identify new SLC superfamily members in the human genome and to elucidate the relationships between SLC families; this will be achieved by mapping sequence, structural and chemical features that distinguish one family from another. The classification into groups of related proteins will be useful for inferring similarities in structural and functional features (e.g., fold, ligand binding site, and molecular mechanism) of uncharacterized proteins based on their characterized aligned homologs. The classification scheme is likely to inform modeling of the SLC transporter structures - a prerequisite for describing their substrate specificities. The second goal is to describe sequence and structure determinants of substrate specificity within selected SLC families. This goal will be accomplished by combining computational methodologies such as sequence analysis, structure comparisons, comparative modeling, ligand docking, and virtual screening, with experimental efforts. The experimental work will be conducted in collaboration with other labs; it will include functional characterization using various assays including ligand uptake and kinetic measurements. The third goal is to utilize the specificity determinants information of the SLC families to develop predictive models for the effects of genetic variation on transporter function, which will be experimentally tested on clinically important substrates. Ultimately, the results obtained in this study will contribute to our understanding of why individuals respond differently to the same drug. In particular, correlation of the study results with clinically observed disease states and variation among individuals in response to drugs can be a significant step toward personalized medicine greatly benefitting public health.