Practice question

Sex-lethal protein contains two conserved RNA recognition motifs binding uridine-rich sequences near regulated splice sites modulating spliceosome assembly. Rather than binding DNA as transcription factor, Sxl interacts with U1 snRNP and U2AF complex to block inclusion of male-specific exon with premature stop codons in its own transcript and transformer. This post-transcriptional RNA-splicing factor activity shifts pattern toward female isoforms. Through precise alternative splicing control, Sxl integrates dosage compensation, germline sexual identity and somatic differentiation, orchestrating entire female program via RNA processing rather than direct transcriptional activation of target genes.