SMN complex Spliceosomal m3G capped snRNA:SMN:SM:Snurportin complex Spliceosomal m3G capped snRNA loaded with the SM complex snRNP nuclear import and release A properly assembled Sm core and the m3G cap structure are prerequisites for small nuclear ribonucleoprotein (snRNP) import into the nucleus. Once imported into the nucleus, the snRNPs are initially concentrated in Cajal bodies (CBs), where there is further processing of the snRNAs plus binding of additional proteins, from CRBs they transit to "speckles", from where they are engaged for pre-mRNA splicing. The SMN complexes in the nucleus are found throughout the nucleoplasm but are particularly concentrated in Gems, the "twins" of the snRNP-rich CBs. Authored: Gillespie, ME, 2007-01-29 20:29:54 GENE ONTOLOGYGO:0051170 Pubmed10531003 Reactome Database ID Release 43191830 Reactome, http://www.reactome.org ReactomeREACT_10010 Reviewed: Luhrmann, R, 2007-04-30 18:31:22