Regulator of nonsense transcripts 3A (UPF3A)

Involved in nonsense-mediated decay (NMD) of mRNAs containing premature stop codons by associating with the atomic exon junction complex (EJC) and functioning as link between the EJC core and NMD machinery. Recruits UPF2 at the cytoplasmic side of the nuclear envelope and the subsequent formation of an UPF1-UPF2- UPF3 surveillance complex (including UPF1 bound to release factors at the stalled ribosome) is believed to activate NMD.

But, UPF3A is shown to be only marginally active in NMD compared to UPF3B. Binds spliced mRNA upstream of exon-exon junctions.