This domain is found in eukaryotes. This domain is about 90 amino acids in length. This domain is found associated with Pfam:PF00076. This domain is part of U1 snRNP, which is the pre-mRNA binding protein of the penta-snRNP spliceosome complex. It extends over a distance of 180 A from its RNA binding domain, wraps around the core domain of U1 snRNP consisting of the seven Sm proteins and finally contacts U1-C, which is crucial for 5'-splice-site recognition.

1: Crystal structure of human spliceosomal U1 snRNP at 5.5 A resolution. Pomeranz Krummel DA, Oubridge C, Leung AK, Li J, Nagai K; Nature. 2009;458:475-480. PMID:19325628