TMEM242 is a scaffold protein that facilitates mitochondrial ATP synthase assembly, primarily through regulation of the c-ring rotor 1. It promotes membrane insertion and oligomerization of subunit c/ATP5MC3 and influences incorporation of additional subunits including MT-ATP6, MT-ATP8, ATP5MJ, and ATP5MK 1. TMEM242 operates cooperatively with TMEM70 in this process; while deletion of either protein alone impairs but does not eliminate ATP synthase assembly, simultaneous deletion of both proteins prevents assembly entirely 1. Beyond ATP synthase, TMEM242 interacts with the mitochondrial complex I assembly (MCIA) complex, suggesting broader roles in respiratory enzyme complex assembly 1. Functionally, TMEM242 is implicated in mitochondrial respiration 2. Disease relevance emerges from zebrafish studies showing tmem242 knockdown increases reactive oxygen species (ROS) through impaired ATP synthase, leading to altered coagulation factor expression and bleeding phenotypes resembling disseminated intravascular coagulation 3. Additionally, TMEM242 expression variations correlate with head circumference in 16p11.2 copy number variant carriers associated with neurodevelopmental disorders 4, though the mechanistic significance requires further investigation in neuronal cell types.