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General Information
Symbol
Dmel\Smn
Species
D. melanogaster
Name
survival motor neuron
Annotation Symbol
CG16725
Feature Type
FlyBase ID
FBgn0036641
Gene Model Status
Stock Availability
Gene Snapshot
survival motor neuron (Smn) encodes the eponymous member of the SMN complex, which functions as an assembly chaperone for Sm-class small nuclear ribonucleoproteins. The SMN complex contains three other 'Gemin' proteins encoded by Gem2, Gem3 and rig. Smn is essential for viability but higher levels of the protein are required for proper neuromuscular development and function. [Date last reviewed: 2019-03-14]
Also Known As

dSMN, l(3)73Ao, survival of motor neurons

Key Links
Genomic Location
Cytogenetic map
Sequence location
3L:16,580,398..16,581,547 [-]
Recombination map

3-44

RefSeq locus
NT_037436 REGION:16580398..16581547
Sequence
Other Genome Views
The following external sites may use different assemblies or annotations than FlyBase.
Function
GO Summary Ribbons
Gene Ontology (GO) Annotations (37 terms)
Molecular Function (2 terms)
Terms Based on Experimental Evidence (1 term)
CV Term
Evidence
References
Terms Based on Predictions or Assertions (1 term)
CV Term
Evidence
References
inferred from electronic annotation with InterPro:IPR010304
(assigned by InterPro )
Biological Process (24 terms)
Terms Based on Experimental Evidence (24 terms)
CV Term
Evidence
References
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
(assigned by UniProt )
inferred from direct assay
(assigned by UniProt )
inferred from mutant phenotype
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
(assigned by UniProt )
inferred from mutant phenotype
(assigned by UniProt )
Terms Based on Predictions or Assertions (0 terms)
Cellular Component (11 terms)
Terms Based on Experimental Evidence (11 terms)
CV Term
Evidence
References
inferred from direct assay
(assigned by UniProt )
inferred from direct assay
(assigned by UniProt )
inferred from direct assay
inferred from direct assay
(assigned by UniProt )
inferred from direct assay
inferred from direct assay
inferred from direct assay
inferred from direct assay
(assigned by UniProt )
inferred from direct assay
inferred from genetic interaction with FLYBASE:Gem3; FB:FBgn0011802
inferred from direct assay
(assigned by UniProt )
inferred from direct assay
Terms Based on Predictions or Assertions (0 terms)
Gene Group (FlyBase)
Protein Family (UniProt)
Belongs to the SMN family. (Q9VV74)
Summaries
Gene Group (FlyBase)
SURVIVAL MOTOR NEURON COMPLEX -
The survival motor neuron (SMN) complex is minimally composed of SMN and Gemin proteins. The SMN complex mediates the assembly of spliceosomal small nuclear ribonucleoproteins (snRNPs). (Adapted from FBrf0228762).
Protein Function (UniProtKB)
The SMN complex plays an essential role in spliceosomal snRNP assembly in the cytoplasm, is required for pre-mRNA splicing in the nucleus and acts as a chaperone that discriminates target and non-target RNAs of Sm proteins. Required for normal expression of spliceosomal snRNAs and for U12 intron splicing. Required in cholinergic neurons, but not in motor neurons, to ensure correct splicing and proper levels of stas mRNA and normal neurotransmitter release by motor neurons (PubMed:23063130 and PubMed:23063131). However, Smn is required in motor neurons, but not in cholinergic neurons, for normal motor behavior but plays no role in synaptic transmission according to PubMed:23103409. In both muscle and neurons, required for the formation of a normal neuromuscular junction (NMJ) structure. Plays a neuron-specific role in long-term homeostatic compensation at the larval NMJ. In the thorax of adult flies, required for Act88F, an indirect flight muscle (IFM)-specific actin, expression and for proper IFM myofibril formation. In nurse cells, oocytes and follicle cells, required to maintain normal organization of nuclear compartments including chromosomes, nucleoli, Cajal bodies, histone locus bodies and heterochromatin. Required for the functional integrity of the cytoplasmic U snRNP body (U body) and P body. Required in dividing postembryonic neuroblasts (pNBs) for the correct basal localization of mira. The tight regulation of its expression is critical for stem cell division, proliferation and differentiation in male germline and developing central nervous system (CNS). Required for tracheal terminal cell lumen formation.
(UniProt, Q9VV74)
Summary (Interactive Fly)

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 and Products
Number of Transcripts
2
Number of Unique Polypeptides
1

Please see the GBrowse view of Dmel\Smn or the JBrowse view of Dmel\Smn for information on other features

To submit a correction to a gene model please use the Contact FlyBase form

Protein Domains (via Pfam)
Isoform displayed:
Pfam protein domains
InterPro name
classification
start
end
Protein Domains (via SMART)
Isoform displayed:
SMART protein domains
InterPro name
classification
start
end
Comments on Gene Model

Gene model reviewed during 5.44

Gene model reviewed during 5.45

Sequence Ontology: Class of Gene
Transcript Data
Annotated Transcripts
Name
FlyBase ID
RefSeq ID
Length (nt)
Assoc. CDS (aa)
FBtr0075395
879
226
FBtr0329921
1086
226
Additional Transcript Data and Comments
Reported size (kB)
Comments
External Data
Crossreferences
Polypeptide Data
Annotated Polypeptides
Name
FlyBase ID
Predicted MW (kDa)
Length (aa)
Theoretical pI
RefSeq ID
GenBank
FBpp0075153
24.6
226
4.93
FBpp0302954
24.6
226
4.93
Polypeptides with Identical Sequences

The group(s) of polypeptides indicated below share identical sequence to each other.

226 aa isoforms: Smn-PA, Smn-PB
Additional Polypeptide Data and Comments
Reported size (kDa)
Comments
External Data
Subunit Structure (UniProtKB)

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).

(UniProt, Q9VV74)
Crossreferences
InterPro - A database of protein families, domains and functional sites
Linkouts
Sequences Consistent with the Gene Model
Mapped Features

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.

External Data
Crossreferences
Eukaryotic Promoter Database - A collection of databases of experimentally validated promoters for selected model organisms.
Linkouts
Expression Data
Expression Summary Ribbons
Colored tiles in ribbon indicate that expression data has been curated by FlyBase for that anatomical location. Colorless tiles indicate that there is no curated data for that location.
For complete stage-specific expression data, view the modENCODE Development RNA-Seq section under High-Throughput Expression below.
Transcript Expression
Polypeptide Expression
immunolocalization
Stage
Tissue/Position (including subcellular localization)
Reference
western blot
Stage
Tissue/Position (including subcellular localization)
Reference
Additional Descriptive Data

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.

Smn is detected by immunolocalization in the wing disc in third instar larvae in a domain overlapping the vg domain. Smn is concentrated in the postsynaptic region of the neuromuscular junction in muscle. It is detected in all tissues examined, including muscle and neurons.

Marker for
 
Subcellular Localization
CV Term
Evidence
References
inferred from direct assay
(assigned by UniProt )
inferred from direct assay
(assigned by UniProt )
inferred from direct assay
inferred from direct assay
(assigned by UniProt )
inferred from direct assay
inferred from direct assay
inferred from direct assay
inferred from direct assay
(assigned by UniProt )
inferred from direct assay
inferred from genetic interaction with FLYBASE:Gem3; FB:FBgn0011802
inferred from direct assay
(assigned by UniProt )
inferred from direct assay
Expression Deduced from Reporters
High-Throughput Expression Data
Associated Tools

GBrowse - Visual display of RNA-Seq signals

View Dmel\Smn in GBrowse 2
RNA-Seq by Region - Search RNA-Seq expression levels by exon or genomic region
Reference
See Gelbart and Emmert, 2013 for analysis details and data files for all genes.
Developmental Proteome: Life Cycle
Developmental Proteome: Embryogenesis
External Data and Images
Linkouts
BDGP expression data - Patterns of gene expression in Drosophila embryogenesis
FLIGHT - Cell culture data for RNAi and other high-throughput technologies
FlyAtlas - Adult expression by tissue, using Affymetrix Dros2 array
Fly-FISH - A database of Drosophila embryo and larvae mRNA localization patterns
Flygut - An atlas of the Drosophila adult midgut
Images
FlyExpress - Embryonic expression images (BDGP data)
  • Stages(s) 1-3
  • Stages(s) 4-6
  • Stages(s) 7-8
  • Stages(s) 9-10
  • Stages(s) 11-12
  • Stages(s) 13-16
Alleles, Insertions, and Transgenic Constructs
Classical and Insertion Alleles ( 9 )
For All Classical and Insertion Alleles Show
 
Other relevant insertions
Transgenic Constructs ( 44 )
For All Alleles Carried on Transgenic Constructs Show
Transgenic constructs containing/affecting coding region of Smn
Transgenic constructs containing regulatory region of Smn
Deletions and Duplications ( 12 )
Phenotypes
For more details about a specific phenotype click on the relevant allele symbol.
Lethality
Allele
Sterility
Allele
Other Phenotypes
Allele
Phenotype manifest in
Allele
Orthologs
Human Orthologs (via DIOPT v8.0)
Homo sapiens (Human) (3)
Species\Gene Symbol
Score
Best Score
Best Reverse Score
Alignment
Complementation?
Transgene?
12 of 15
Yes
Yes
2  
7 of 15
No
Yes
2  
1 of 15
No
No
Model Organism Orthologs (via DIOPT v8.0)
Mus musculus (laboratory mouse) (2)
Species\Gene Symbol
Score
Best Score
Best Reverse Score
Alignment
Complementation?
Transgene?
13 of 15
Yes
Yes
1 of 15
No
No
Rattus norvegicus (Norway rat) (2)
12 of 13
Yes
Yes
1 of 13
No
No
Xenopus tropicalis (Western clawed frog) (3)
8 of 12
Yes
Yes
2 of 12
No
Yes
1 of 12
No
No
Danio rerio (Zebrafish) (2)
13 of 15
Yes
Yes
1 of 15
No
No
Caenorhabditis elegans (Nematode, roundworm) (1)
10 of 15
Yes
Yes
Arabidopsis thaliana (thale-cress) (1)
1 of 9
Yes
No
Saccharomyces cerevisiae (Brewer's yeast) (0)
No records found.
Schizosaccharomyces pombe (Fission yeast) (1)
1 of 12
Yes
No
Orthologs in Drosophila Species (via OrthoDB v9.1) ( EOG09190IL5 )
Organism
Common Name
Gene
AAA Syntenic Ortholog
Multiple Dmel Genes in this Orthologous Group
Drosophila suzukii
Spotted wing Drosophila
Drosophila simulans
Drosophila sechellia
Drosophila erecta
Drosophila yakuba
Drosophila ananassae
Drosophila pseudoobscura pseudoobscura
Drosophila persimilis
Drosophila willistoni
Drosophila virilis
Drosophila mojavensis
Drosophila grimshawi
Orthologs in non-Drosophila Dipterans (via OrthoDB v9.1) ( EOG091508XJ )
Organism
Common Name
Gene
Multiple Dmel Genes in this Orthologous Group
Musca domestica
House fly
Glossina morsitans
Tsetse fly
Glossina morsitans
Tsetse fly
Glossina morsitans
Tsetse fly
Lucilia cuprina
Australian sheep blowfly
Mayetiola destructor
Hessian fly
Aedes aegypti
Yellow fever mosquito
Anopheles darlingi
American malaria mosquito
Anopheles gambiae
Malaria mosquito
Culex quinquefasciatus
Southern house mosquito
Orthologs in non-Dipteran Insects (via OrthoDB v9.1) ( EOG090W09S7 )
Organism
Common Name
Gene
Multiple Dmel Genes in this Orthologous Group
Bombyx mori
Silkmoth
Danaus plexippus
Monarch butterfly
Heliconius melpomene
Postman butterfly
Apis florea
Little honeybee
Apis mellifera
Western honey bee
Bombus impatiens
Common eastern bumble bee
Bombus terrestris
Buff-tailed bumblebee
Linepithema humile
Argentine ant
Megachile rotundata
Alfalfa leafcutting bee
Nasonia vitripennis
Parasitic wasp
Pediculus humanus
Human body louse
Rhodnius prolixus
Kissing bug
Cimex lectularius
Bed bug
Acyrthosiphon pisum
Pea aphid
Zootermopsis nevadensis
Nevada dampwood termite
Orthologs in non-Insect Arthropods (via OrthoDB v9.1) ( EOG090X0L1U )
Organism
Common Name
Gene
Multiple Dmel Genes in this Orthologous Group
Strigamia maritima
European centipede
Strigamia maritima
European centipede
Ixodes scapularis
Black-legged tick
Ixodes scapularis
Black-legged tick
Stegodyphus mimosarum
African social velvet spider
Tetranychus urticae
Two-spotted spider mite
Tetranychus urticae
Two-spotted spider mite
Daphnia pulex
Water flea
Orthologs in non-Arthropod Metazoa (via OrthoDB v9.1) ( None identified )
No non-Arthropod Metazoa orthologies identified
Paralogs
Paralogs (via DIOPT v8.0)
Drosophila melanogaster (Fruit fly) (1)
2 of 10
Human Disease Associations
FlyBase Human Disease Model Reports
Disease Model Summary Ribbon
Disease Ontology (DO) Annotations
Models Based on Experimental Evidence ( 19 )
Allele
Disease
Evidence
References
Potential Models Based on Orthology ( 5 )
Modifiers Based on Experimental Evidence ( 2 )
Disease Associations of Human Orthologs (via DIOPT v8.0 and OMIM)
Note that ortholog calls supported by only 1 or 2 algorithms (DIOPT score < 3) are not shown.
Functional Complementation Data
Functional complementation data is computed by FlyBase using a combination of the orthology data obtained from DIOPT and OrthoDB and the allele-level genetic interaction data curated from the literature.
Interactions
Summary of Physical Interactions
esyN Network Diagram
Show neighbor-neighbor interactions:
Select Layout:
Legend:
Protein
RNA
Selected Interactor(s)
Interactions Browser

Please see the Physical Interaction reports below for full details
protein-protein
Physical Interaction
Assay
References
Summary of Genetic Interactions
esyN Network Diagram
esyN Network Key:
Suppression
Enhancement

Please look at the allele data for full details of the genetic interactions
Starting gene(s)
Interaction type
Interacting gene(s)
Reference
Starting gene(s)
Interaction type
Interacting gene(s)
Reference
External Data
Subunit Structure (UniProtKB)
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).
(UniProt, Q9VV74 )
Linkouts
BioGRID - A database of protein and genetic interactions.
DroID - A comprehensive database of gene and protein interactions.
InterologFinder - Protein-protein interactions (PPI) from both known and predicted PPI data sets.
MIST (genetic) - An integrated Molecular Interaction Database
MIST (protein-protein) - An integrated Molecular Interaction Database
Pathways
Signaling Pathways (FlyBase)
Metabolic Pathways
External Data
Linkouts
KEGG Pathways - Wiring diagrams of molecular interactions, reactions and relations.
Genomic Location and Detailed Mapping Data
Chromosome (arm)
3L
Recombination map

3-44

Cytogenetic map
Sequence location
3L:16,580,398..16,581,547 [-]
FlyBase Computed Cytological Location
Cytogenetic map
Evidence for location
73A9-73A9
Limits computationally determined from genome sequence between P{lacW}l(3)j10E8j10E8&P{PZ}l(3)1053210532 and P{PZ}Baldspot02281
Experimentally Determined Cytological Location
Cytogenetic map
Notes
References
Experimentally Determined Recombination Data
Location
Left of (cM)
Right of (cM)
Notes
Stocks and Reagents
Stocks (11)
Genomic Clones (11)
 

Please Note FlyBase no longer curates genomic clone accessions so this list may not be complete

cDNA Clones (22)
 

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.

cDNA clones, fully sequenced
BDGP DGC clones
Other clones
Drosophila Genomics Resource Center cDNA clones

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.

cDNA Clones, End Sequenced (ESTs)
RNAi and Array Information
Linkouts
DRSC - Results frm RNAi screens
GenomeRNAi - A database for cell-based and in vivo RNAi phenotypes and reagents
Antibody Information
Laboratory Generated Antibodies
Commercially Available Antibodies
 
Other Information
Relationship to Other Genes
Source for database identify of

Source for identity of: Smn CG16725

Source for database merge of

Source for merge of: Smn l(3)73Ao

Additional comments

Source for identity of Smn CG16725 was sequence comparison ( date:001007 ).

Other Comments

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.

Origin and Etymology
Discoverer
Etymology
Identification
External Crossreferences and Linkouts ( 40 )
Sequence Crossreferences
NCBI Gene - Gene integrates information from a wide range of species. A record may include nomenclature, Reference Sequences (RefSeqs), maps, pathways, variations, phenotypes, and links to genome-, phenotype-, and locus-specific resources worldwide.
GenBank Nucleotide - A collection of sequences from several sources, including GenBank, RefSeq, TPA, and PDB.
GenBank Protein - A collection of sequences from several sources, including translations from annotated coding regions in GenBank, RefSeq and TPA, as well as records from SwissProt, PIR, PRF, and PDB.
RefSeq - A comprehensive, integrated, non-redundant, well-annotated set of reference sequences including genomic, transcript, and protein.
UniProt/Swiss-Prot - Manually annotated and reviewed records of protein sequence and functional information
Other crossreferences
BDGP expression data - Patterns of gene expression in Drosophila embryogenesis
Drosophila Genomics Resource Center - Drosophila Genomics Resource Center (DGRC) cDNA clones
Eukaryotic Promoter Database - A collection of databases of experimentally validated promoters for selected model organisms.
Fly-FISH - A database of Drosophila embryo and larvae mRNA localization patterns
Flygut - An atlas of the Drosophila adult midgut
GenomeRNAi - A database for cell-based and in vivo RNAi phenotypes and reagents
InterPro - A database of protein families, domains and functional sites
KEGG Genes - Molecular building blocks of life in the genomic space.
modMine - A data warehouse for the modENCODE project
Linkouts
BioGRID - A database of protein and genetic interactions.
DPiM - Drosophila Protein interaction map
DroID - A comprehensive database of gene and protein interactions.
DRSC - Results frm RNAi screens
FLIGHT - Cell culture data for RNAi and other high-throughput technologies
FlyAtlas - Adult expression by tissue, using Affymetrix Dros2 array
FlyCyc Genes - Genes from a BioCyc PGDB for Dmel
FlyMine - An integrated database for Drosophila genomics
Interactive Fly - A cyberspace guide to Drosophila development and metazoan evolution
InterologFinder - Protein-protein interactions (PPI) from both known and predicted PPI data sets.
KEGG Pathways - Wiring diagrams of molecular interactions, reactions and relations.
MIST (genetic) - An integrated Molecular Interaction Database
MIST (protein-protein) - An integrated Molecular Interaction Database
Synonyms and Secondary IDs (13)
Reported As
Symbol Synonym
Secondary FlyBase IDs
  • FBgn0025499
Datasets (0)
Study focus (0)
Experimental Role
Project
Project Type
Title
References (119)