This domain is found at the C-terminal end of U4/U6 and U4/U5/U6- small nuclear ribonucleoprotein Prp3, part of the tri-RNA complex that form the spliceosome. Prp3 plays a key role in the recognition of the snRNA duplex. This binding domain, highly conserved among eukaryotes, interacts with the 3' end of U6 snRNA. It adopts a ferredoxin-like fold, showing a five-stranded mixed beta-sheet with three alpha-helices, two of them running parallel to the beta-strands on one side of the sheet and one on the other. This fold is extended with a long beta-hairpin, an extra beta-strand, an helix and a final loop at the C terminus. It is located C-terminal to Pfam:PF08572 [1-4].

1: Molecular architecture of the human U4/U6.U5 tri-snRNP. Agafonov DE, Kastner B, Dybkov O, Hofele RV, Liu WT, Urlaub H, Luhrmann R, Stark H; Science. 2016;351:1416-1420. PMID:26912367

2: Cryo-EM structure of the yeast U4/U6.U5 tri-snRNP at 3.7 A resolution. Nguyen THD, Galej WP, Bai XC, Oubridge C, Newman AJ, Scheres SHW, Nagai K; Nature. 2016;530:298-302. PMID:26829225

3: A composite double-/single-stranded RNA-binding region in protein Prp3 supports tri-snRNP stability and splicing. Liu S, Mozaffari-Jovin S, Wollenhaupt J, Santos KF, Theuser M, Dunin-Horkawicz S, Fabrizio P, Bujnicki JM, Luhrmann R, Wahl MC; Elife. 2015;4:e07320. PMID:26161500

4: The 3.8 A structure of the U4/U6.U5 tri-snRNP: Insights into spliceosome assembly and catalysis. Wan R, Yan C, Bai R, Wang L, Huang M, Wong CC, Shi Y; Science. 2016;351:466-475. PMID:26743623