DDX20
Function
The SMN complex catalyzes the assembly of small nuclear ribonucleoproteins (snRNPs), the building blocks of the spliceosome, and thereby plays an important role in the splicing of cellular pre-mRNAs. Most spliceosomal snRNPs contain a common set of Sm proteins SNRPB, SNRPD1, SNRPD2, SNRPD3, SNRPE, SNRPF and SNRPG that assemble in a heptameric protein ring on the Sm site of the small nuclear RNA to form the core snRNP (Sm core). In the cytosol, the Sm proteins SNRPD1, SNRPD2, SNRPE, SNRPF and SNRPG are trapped in an inactive 6S pICln-Sm complex by the chaperone CLNS1A that controls the assembly of the core snRNP. To assemble core snRNPs, the SMN complex accepts the trapped 5Sm proteins from CLNS1A forming an intermediate. Binding of snRNA inside 5Sm triggers eviction of the SMN complex, thereby allowing binding of SNRPD3 and SNRPB to complete assembly of the core snRNP. May also play a role in the metabolism of small nucleolar ribonucleoprotein (snoRNPs).
Sequence Similarities
Belongs to the DEAD box helicase family. DDX20 subfamily.
Tissue Specificity
Ubiquitous.
Cellular localization
- Cytoplasm
- Nucleus
- Gem
- Localized in subnuclear structures next to coiled bodies, called Gemini of Cajal bodies (Gems).
Alternative names
DP103, GEMIN3, DDX20, Probable ATP-dependent RNA helicase DDX20, Component of gems 3, DEAD box protein 20, DEAD box protein DP 103, Gemin-3