C-terminal m3G cap-binding domain of nuclear import adaptor snurportin-1
Snurportin-1 (SPN1 or SNUPN) is a nuclear import adaptor for m3G-capped spliceosomal U small nucleoproteins (snRNPs), which are assembled in the cytoplasm. After capping and assembly, the U snRNPs are transported into the nucleus by SPN1 and importin beta; SPN1 is then returned to the cytoplasm by exportin 1 (CRM1), which also transports the non-capped U snRNPs. The U snRNPs are essential elements of the spliceosome, which catalyzes the excision of introns and the ligation of exons to form a mature mRNA. SPN1 contains two domains, an N-terminal importin beta-binding (IBB) domain and a C-terminal m3G cap-binding domain.
Jiyao W et al.(2023). "The conserved domain database in 2023.",