Mutations in transporters can impact an individual’s response to drugs and cause many diseases. Few variants in transporters have been evaluated for their functional impact. Here, we combine saturation mutagenesis and multi-phenotypic screening to dissect the impact of 11,213 missense single-amino-acid deletions, and synonymous variants across the 554 residues of OCT1, a key liver xenobiotic transporter. By quantifying in parallel expression and substrate uptake, we find that most variants exert their primary effect on protein abundance, a phenotype not commonly measured alongside function. Using our mutagenesis results combined with structure prediction and molecular dynamic simulations, we develop accurate structure-function models of the entire transport cycle, providing biophysical characterization of all known and possible human OCT1 polymorphisms. This work provides a complete functional map of OCT1 variants along with a framework for integrating functional genomics, biophysical modeling, and human genetics to predict variant effects on disease and drug efficacy.

转运蛋白的突变会影响个体对药物的反应并导致许多疾病。很少有转运蛋白的变体对其功能影响进行了评估。在这里，我们结合饱和诱变和多表型筛选来剖析 11,213 个错义单氨基酸缺失以及 OCT1（一种关键的肝脏异生素转运蛋白）554 个残基上的同义变异的影响。通过并行定量表达和底物摄取，我们发现大多数变异对蛋白质丰度产生主要影响，而这种表型通常不与功能一起测量。利用我们的诱变结果结合结构预测和分子动力学模拟，我们开发了整个运输周期的精确结构功能模型，提供所有已知和可能的人类 OCT1 多态性的生物物理表征。这项工作提供了 OCT1 变体的完整功能图谱，以及整合功能基因组学、生物物理模型和人类遗传学的框架，以预测变体对疾病和药物疗效的影响。