MGAT1 encodes an alpha-1,3-mannosyl-glycoprotein 2-beta-N-acetylglucosaminyltransferase that catalyzes the first step in converting high-mannose to hybrid and complex N-glycans, a process essential for normal protein glycosylation. The enzyme localizes to the Golgi apparatus and can be translocated to mitochondria under specific metabolic conditions, where it regulates oxidative phosphorylation in regulatory T cells via N-glycosylation of progranulin and HYOU1 1. MGAT1 is regulated by the Wnt/β-catenin signaling pathway, and biantennary N-glycans generated by MGAT1 are important for cell-surface tetraspanin expression and trafficking 2. In disease contexts, MGAT1 has divergent roles: in pancreatic ductal adenocarcinoma, high MGAT1 expression is associated with better patient prognosis and suppresses cell proliferation and migration 3, whereas in triple-negative breast cancer, MGAT1 overexpression promotes immune evasion by facilitating CD73 glycosylation and membrane translocation, suppressing CD8+ T cell function 4. In gastric cancer, reduced MGAT1 expression is associated with poorer survival outcomes 5. Preclinically, W-GTF01, a specific MGAT1 inhibitor, sensitizes triple-negative breast cancer to anti-PD-L1 therapy by restoring CD8+ T cell function 4, representing a therapeutic strategy for immune-cold tumors. Genome-wide association studies have identified MGAT1 variants associated with weight in European populations 6, and Mendelian randomization analysis suggests MGAT1 as a potential therapeutic target for atherosclerosis 7.