The function of TMEM242 (transmembrane protein 242, Ensembl gene identifier ENSG00000215712) is as follows. Scaffold protein that participates in the c-ring assembly of mitochondrial ATP synthase (F(1)F(0) ATP synthase or complex V) by facilitating the membrane insertion and oligomer formation of the subunit c/ATP5MC3 (PubMed:33753518). Participates in the incorporation of the c-ring into vestigial complexes (PubMed:33753518). Additionally influences the incorporation of subunits MT-ATP6, MT-ATP8, ATP5MJ, and ATP5MK in the ATP synthase (PubMed:33753518). .