This study investigates the mechanism by which two coding variants of apolipoprotein L1 (APOL1), G1 and G2, contribute to kidney disease in African Americans. The authors used three experimental models and a small molecule blocker of APOL1 protein, VX-147, to identify the upstream mechanism of G1-induced cytotoxicity. They found that G1-mediated Na⁺/K⁺ transport triggers activation of GPCR/IP3-mediated calcium release from the endoplasmic reticulum (ER), impairs mitochondrial ATP production, and inhibits translation, all of which are reversed by VX-147. In human urine-derived podocyte-like epithelial cells (HUPECs) and primary podocytes from APOL1 G1 transgenic mice, G1 caused cytotoxicity that was also reversible by VX-147. These results establish APOL1-mediated Na⁺/K⁺ transport as the proximal driver of APOL1-mediated kidney disease, providing a unified model for the cytotoxicity induced by APOL1 variants. The study also reveals two new cellular functions of APOL1 G1: triggering ER Ca²⁺ release via Gαq-PLC/IP3R/RYR signaling and inhibiting amino acid import, leading to intracellular amino acid deficiency.This study investigates the mechanism by which two coding variants of apolipoprotein L1 (APOL1), G1 and G2, contribute to kidney disease in African Americans. The authors used three experimental models and a small molecule blocker of APOL1 protein, VX-147, to identify the upstream mechanism of G1-induced cytotoxicity. They found that G1-mediated Na⁺/K⁺ transport triggers activation of GPCR/IP3-mediated calcium release from the endoplasmic reticulum (ER), impairs mitochondrial ATP production, and inhibits translation, all of which are reversed by VX-147. In human urine-derived podocyte-like epithelial cells (HUPECs) and primary podocytes from APOL1 G1 transgenic mice, G1 caused cytotoxicity that was also reversible by VX-147. These results establish APOL1-mediated Na⁺/K⁺ transport as the proximal driver of APOL1-mediated kidney disease, providing a unified model for the cytotoxicity induced by APOL1 variants. The study also reveals two new cellular functions of APOL1 G1: triggering ER Ca²⁺ release via Gαq-PLC/IP3R/RYR signaling and inhibiting amino acid import, leading to intracellular amino acid deficiency.