TRA2B encodes TRA2β (transformer 2 beta homolog), a serine/arginine-rich splicing regulator that controls alternative pre-mRNA splicing in a concentration-dependent manner 1. The protein functions as both an activator and suppressor of exon inclusion, with critical roles in autoregulation through an ultraconserved poison exon (PE) mechanism 23. TRA2β undergoes autoregulatory splicing where PE inclusion targets transcripts for nonsense-mediated decay, maintaining proper protein levels essential for cellular function 3. This autoregulation is crucial for male fertility, as PE deletion causes azoospermia due to toxic TRA2β protein accumulation during meiotic prophase 3. The gene produces multiple splice isoforms, with TRA2β1 being the functional protein and TRA2β4 serving as a functional RNA 4. TRA2β regulates T cell receptor sensitivity through PE splicing, acting as a gatekeeper for T cell fate decisions during immune responses 2. In cancer contexts, TRA2β is frequently amplified across multiple malignancies, and decreased PE inclusion contributes to oncogenic upregulation 15. Pathogenic variants in TRA2B cause neurodevelopmental disorders with seizures and developmental delay 6. The protein cooperates with other splicing regulators like SRRM2 and SON to control GC-rich exon inclusion important for myeloid differentiation 7.