Zc3h13/Flacc is required for adenosine methylation by bridging the mRNA-binding factor Rbm15/Spenito to the mA machinery component Wtap/Fl(2)d.

N-6-methyladenosine (m(6)A) is the most abundant mRNA modification in eukaryotes, playing crucial roles in multiple biological processes. m(6)A is catalyzed by the activity of methyltransferase-like 3 (Mettl3), which depends on additional proteins whose precise functions remain poorly understood. Here we identified Zc3h13 (zinc finger CCCH domain-containing protein 13)/Flacc [Fl(2)d-associated complex component] as a novel interactor of m(6)A methyltransferase complex components in Drosophila and mice. Like other components of this complex, Flacc controls m(6)A levels and is involved in sex determination in Drosophila. We demonstrate that Flacc promotes m(6)A deposition by bridging Fl(2)d to the mRNA-binding factor Nito. Altogether, our work advances the molecular understanding of conservation and regulation of the m(6)A machinery.