Gem-associated protein 7 (Gemin-7) (SIP3)
1_MQTPV 6_ NIPVP 11_ VLRLP 16_ RGPDG 21_ FSRGF 26_ APDGR 31_ RAPLR 36_ PEVPE 41_ IQECP 46_ IAQES 51_ LESQE 56_ QRARA 61_ ALRER 66_ YLRSL 71_ LAMVG 76_ HQVSF 81_ TLHEG 86_ VRVAA 91_ HFGAT 96_ DLDVA 101_ NFYVS 106_ QLQTP 111_ IGVQA 116_ EALLR 121_ CSDII 126_SYTFK
1: 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