Small Nuclear Ribonucleoprotein 48kDa (SNRNP48)

SNRNP48, Contains 1 CHHC-type zinc finger. U11 and U12 snRNPs bind U12-type pre-mRNAs as a preformed di-snRNP complex, simultaneously recognizing the 5' splice site and branchpoint sequence. Thus, within the U12-type prespliceosome, U11/U12 components form a molecular bridge connecting both ends of the intron. U11/U12 snRNPs lack all known U1 snRNP proteins but contain seven novel proteins (i.e., 65K, 59K, 48K, 35K, 31K, 25K, 20K) not found in the major spliceosome, four of which (59K, 48K, 35K, and 25K) are U11-associated. Thus, protein-protein and protein-RNA interactions contributing to 5' splice site recognition and/or intron bridging appear to differ significantly in the minor versus major prespliceosome. The majority of U11/U12 proteins are highly conserved in organisms known to contain U12-type introns.