dSMN, l(3)73Ao, survival of motor neurons
RNA binding protein involved, along with Gemins, in the assembly of the small nuclear ribonucleoproteins that constitute the spliceosome - neuromuscular junction protein required in both neurons and muscle for normal junctional morphology
Gene model reviewed during 5.44
Gene model reviewed during 5.45
Homodimer (via C-terminal region) (PubMed:11113446, PubMed:12783845, PubMed:22813737). Part of the core SMN complex, which seems to be composed of Smn and Gem2 only (PubMed:18621711, PubMed:23333303). The SMN complex associates with the entire set of spliceosomal snRNP Sm proteins, SmB, SmD1, SmD2, SmD3, SmE, SmF and SmG, and with the snRNP-specific proteins snRNP-U1-70K, U2A, snf/U1A and U5-116KD (PubMed:18621711, PubMed:23333303). Associates weakly with Gem3 (PubMed:18621711). Interacts with SmB and SmD1; the interaction is favored by methylation of the Sm proteins (PubMed:16753561, PubMed:18369183). Interacts with Actn; the interaction occurs in thoracic tissues and in adult flies (PubMed:17353360). Interacts with Rpp20 (PubMed:14715275). Interacts with msk and Snup; these interactions are RNA-dependent (PubMed:23885126).
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\Smn using the Feature Mapper tool.
While Smn is a ubiquitously expressed protein, the levels are modulated in different tissues. Smn is expressed in the ventral ganglion of the developing larval CNS. In early first instar larvae, it is ubiquitous and located in puncate bodies. During late first instar and second instar stages, levels increase in cells that correspond to quiescent postembryonic neuroblasts (pNBs). Smn accumulation increases, with the highest expression found in the cytoplasm of second and third instar dividing pNBs. After division, levels are higher in the neuroblast than in the ganglion mother cell. Levels decrease in a gradient through the daughter cells until reaching a basal level in differentiated neurons and glia. In the larval brain, Smn is enriched in type ID, IA, and all mira-staining neuroblasts of the brain lobes. Smn is expressed in the adult testis where it is localized to the apical tip. Smn is enriched in germline stem cells (GSCs) and levels decrease as cells differentiate, forming a gradient. Staining is undetectable in hub cells, is very high in GSCs, remains high in gonialblasts and spermatogonia, and decreses dramatically in spermatocytes.
GBrowse - Visual display of RNA-Seq signalsView Dmel\Smn in GBrowse 2
Please Note This section lists cDNAs and ESTs that fall within the genomic extent of the gene model, which may include cDNAs and ESTs of genes within introns, or of overlapping genes. Please see GBrowse for alignment of the cDNAs and ESTs to the gene model.
For each fully sequenced cDNA the DGRC maintains various forms of the cDNA (e.g tagged or untagged) in several different host vectors for subsequent cloning and expression in Drosophila and Drosophila cell lines.
The disruption of motor neurons and muscles seen in Smn mutants is a secondary consequence of a primary dysfunction of sensory-motor network activity: Smn function must be restored in both proprioceptive neurons and cholinergic interneurons to rescue Smn mutant phenotypes.
Smn mutant animals show progressive loss of mobility and increasingly uncoordinated movement.
Mutants show defects at the neuromuscular junction.