The translational control pathway of msl-2 mRNA in sex determination in Drosophila. The main features of the gene are shown, including the upstream ORF (uORF) with its consensus sequence, two poly(U) stretches, the translation start and stop codons and the poly(A) tail, together with the proteins involved in this regulation. eIF, eukaryotic translation initiation factor; msl-2, male-specific lethal-2; PABP, poly(A) binding protein; PIC, 43S preinitiation complex; Sxl, Sex lethal; UNR, co-repressor protein Upstream of N-Ras; UTR, untranslated region. Positive and negative influences of the binding of Sxl to poly(U) stretches in 5' and 3' UTRs are indicated by plus and minus signs, respectively. The potential interaction between Sxl and PIC is indicated by a dashed double-headed arrow.