Zc3h13/Flacc is required for adenosine methylation by bridging the mRNA binding factor Rbm15/Spenito to other components of the m6A machinery

N6-methyladenosine (m6A) is an abundant RNA modification in eukaryotes, playing crucial roles in multiple biological processes. m6A is catalyzed by the activity of Mettl3, which depends on additional proteins whose precise functions remain poorly understood. Here we identified Flacc/Zc3h13 as a novel interactor of m6A methyltransferase complex components in Drosophila and mouse. Like other components, Flacc controls m6A levels and is involved in sex determination in Drosophila. We demonstrate that Flacc promotes the recruitment of the methyltransferase to mRNA by bridging Fl(2)d to the mRNA binding factor Spenito. Altogether, our work advances our molecular understanding of conservation and regulation of the m6A machinery.