Zc3h13/Flacc is required for adenosine methylation by bridging the mRNA-binding factor Rbm15/Spenito to the m 6 A machinery component Wtap/Fl(2)d.

N 6 -methyladenosine (m6 A) is the most abundant mRNA modification in eukaryotes, playing crucial roles in multiple biological processes. m6 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 m6 A methyltransferase complex components in Drosophila and mice. Like other components of this complex, Flacc controls m6 A levels and is involved in sex determination in Drosophila We demonstrate that Flacc promotes m6 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 m6 A machinery.