National Natural Science Foundation of China (NSFC)
32471252
中国
Ministry of Science and Technology (MoST, China)
2021YFA1302300
中国
引用
ジャーナル: Nat Struct Mol Biol / 年: 2025 タイトル: Structural basis of G6P/Pi transport and inhibition in SLC37A4. 著者: Dong Zhou / Yang Zhang / Nanhao Chen / Shitang Huang / Chen Song / Zhe Zhang / 要旨: Glycogen storage disease type Ib (GSD-Ib), caused by loss-of-function mutations in the endoplasmic reticulum transporter SLC37A4, disrupts glucose homeostasis through impaired glucose-6-phosphate ...Glycogen storage disease type Ib (GSD-Ib), caused by loss-of-function mutations in the endoplasmic reticulum transporter SLC37A4, disrupts glucose homeostasis through impaired glucose-6-phosphate (G6P)/phosphate (Pi) antiport. Despite its central role in glycogen metabolism and immune regulation, the structural mechanisms governing SLC37A4's transport cycle and pathological dysfunction remain elusive. Here we report cryo-electron microscopy structures of human SLC37A4 in four functional states, capturing conformational transitions between lumen-facing and cytoplasm-facing states. Combined with mutational analysis, molecular dynamics simulations and functional assays, we identify a conserved substrate-binding pocket that alternately accommodates G6P and Pi through electrostatic complementarity and domain-dependent interactions. We further demonstrate that the high-affinity inhibitor S-4048 sterically occludes the cytoplasmic entry pathway by trapping the transporter in a cytoplasm-facing conformation. Our work elucidates the molecular pathology of GSD-Ib-linked mutations and provides a structural framework for developing therapies targeting this transporter in metabolic diseases.