The survival motor neuron (SMN) complex assembles the heptameric Sm protein ring onto the Sm site of spliceosomal snRNAs in the cytoplasm, the key step of Sm-class snRNP biogenesis. SMN oligomerizes and binds Gemin2, which holds a pentamer of Sm proteins; Gemin5 recognizes the snRNA, and Gemin3 is a DEAD-box helicase subunit. Drosophila has a reduced set of Gemin proteins compared with vertebrates and carries three Gemin4 paralogs (Glos/Gemin4a, Gem4b, Gem4c); FlyBase defines SMN complex variants that differ in which Gemin4 paralog they contain. Loss of Smn in flies causes defects in snRNP assembly, motor function and viability, modelling spinal muscular atrophy.
FlyBase groups the Gemins (GEM) and three SMN complex variants (SMN-C with Gem4a/Glos, SMN-C-4B with Gem4b, SMN-C-4C). The FlyBase SMN-C-4C group lists only Smn, Gem2, Gem3 and rig and omits Gem4c itself; Gem4c is assigned to the Gemin4c variant here on the basis of the group name and its GEM membership. Whether one complex holds exactly one Gemin4 paralog is inferred from the FlyBase variant definitions. Sm proteins, the substrate of the complex, are in dmel_spliceosome. No molecular function is assigned: the SMN complex assembles Sm rings onto snRNAs, which is captured as a process, and the RNA helicase activity inferred for Gem3 (IBA) is not established for the fly protein. FlyBase groups realized by this module: GEM (FBgg0000470), SMN-CPX (FBgg0001830). Subgroups folded into it: SMN-C, SMN-C-4B, SMN-C-4C. Participants were generated from the FlyBase gene-group membership and mapped to UniProtKB by projects/FLYBASE_GENE_GROUPS/generate_modules.py from module_specs/dmel_smn_complex.yaml. None of the member genes has a gene review in this repository yet.
All recommended fields populated.
✗ none found
No MODULE:dmel_smn_complex deep-research report alongside the module YAML.
✓ every leaf node grounds to a representative protein.
✓ every declared conforms_to bundle matches its template motif.
No functional claims were checked. This does not establish consistency with gene or family reviews.
2 complete review(s) · 2 with deep research · 5 missing review · 0 reviewed but lacking deep research
| Gene | Review | Complete | Deep research |
|---|---|---|---|
| Gem4c Q8IRS9 | ✗ | — | — |
| Gem4b Q8IRT0 | ✗ | — | — |
| Gem3 Q9V3C4 | ✗ | — | — |
| Gem2 Q9VVX0 | ✗ | — | — |
| Glos Q9W4N9 | ✗ | — | — |
| rig Q86BY9 | ✓ | ✓ | ✓ |
| Smn Q9VV74 | ✓ | ✓ | ✓ |
SMN-Gemin complex that loads Sm rings onto snRNAs during snRNP assembly, with alternative Gemin4 paralogs.
SMN, Gemin2, the helicase Gemin3 and the snRNA-binding Gemin5 (rig).