Project Summary Inward Rectifier K+ channels (KIR) play key roles in the operation of cells in neuromuscular and other tissue. Pathogenic variants are linked to numerous neurological, cardiovascular, and metabolic disorders. Although some variants cause gating defects in KIR by altering ligand regulation or ion permeation, there is growing evidence that many –perhaps most– variants cause defects in folding and trafficking of KIR. Despite the central role for folding and trafficking in the disease etiology, there have been to date no comprehensive large-scale studies that determine sequence and structural determinants of KIR trafficking and functional robustness. Here we provide the first comprehensive assessment of missense and topological mutations’ effects on KIR trafficking and function. Acquisition of these data is the required first step to build quantitative biophysical model of the sequence, structure, and function relationship in KIR. These models will be useful to understand the mechanistic basis for KIR mutation phenotypes, to predict their pathogenicity, and to identify new treatment strategies for KIR- linked disorders. These models will also pave the way for rational engineering of KIR as chemogenetic reagents that can be used to study functional roles of K+ channels in intact tissues.