TIMMDC1 (translocase of inner mitochondrial membrane domain containing 1) is a crucial chaperone protein that facilitates the assembly of mitochondrial NADH:ubiquinone oxidoreductase complex (complex I) 1. The protein localizes to the mitochondrial inner membrane and specifically participates in constructing the membrane arm of complex I 2. TIMMDC1's stability is regulated by C9orf72, which recruits the prohibitin complex to prevent m-AAA protease-dependent degradation of TIMMDC1 1. Beyond complex I assembly, TIMMDC1 functions as a respirasome assembly factor, with its depletion leading to accumulation of respirasome subcomplexes in both cell lines and patient-derived cells with disease-causing TIMMDC1 mutations 2. The protein plays important roles in cellular energy metabolism, as TIMMDC1 knockdown significantly reduces mitochondrial complex I activity, mitochondrial respiration, ATP-linked oxygen consumption, and glycolysis activity 3. Clinically, TIMMDC1 is associated with mitochondrial complex I deficiency and has emerged as a potential biomarker in various pathological conditions including septic cardiomyopathy, gastric cancer, and esophageal squamous cell carcinoma 435. The protein's expression is regulated by m6A methylation through METTL3, influencing cellular proliferation and immune responses 6.