InterPro domain: IPR040812

This is 1B domain of UPF1 which has a regulatory role. It suffers conformational changes from an inhibitory state to a transition-state complex that modulate RNA binding [ 1 , 2 ].

UPF1 (or regulator of nonsense transcripts 1 homologue) is an essential RNA helicase that detects mRNAs containing premature stop codons and triggers their degradation. Together with UPF2 and UPF3, forms a surveillance complex, in which UPF2 acts as a bridge between UPF1 and UPF3. UPF2 and UPF3 are nonenzymatic components of the complex that stimulate the activity of UPF1 [ 3 ]. UPF1 has a N-terminal cysteine/histidine-rich zinc-binding domain (CH/ZBD), a regulatory 1B domain, followed by a helicase core that belongs to superfamily 1 (SF1).

1. Molecular mechanisms for the RNA-dependent ATPase activity of Upf1 and its regulation by Upf2. Mol Cell
2. Unusual bipartite mode of interaction between the nonsense-mediated decay factors, UPF1 and UPF2. EMBO J. 41, 693-703