FB2026_02 , released June 18, 2026
FB2026_02 , released June 18, 2026
Gene: Dmel\skl
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General Information
Symbol
Dmel\skl
Species
D. melanogaster
Name
sickle
Annotation Symbol
CG13701
Feature Type
protein_coding_gene
FlyBase ID
FBgn0036786
Gene Model Status
Current
Stock Availability
36 publicly available
Gene Summary
sickle (skl) encodes a member of the inhibitor of apoptotic protein antagonists. It is partially involved in the apoptosis of some larval neurons during metamorphosis. [Date last reviewed: 2019-03-14] (FlyBase Gene Snapshot)
All Summaries
Key Links
Genomic Location
Cytogenetic map
75C6-75C6
Sequence location
Recombination map
3-45
RefSeq locus
NT_037436 REGION:18438561..18439942
Sequence
Get Decorated FASTA
Genomic Maps
Other Genome Views
The following external sites may use different assemblies or annotations than FlyBase.
NCBI
UCSC
Ensembl
PopFly
Function
Gene Ontology (GO) Annotations (3 terms)
Molecular Function (0 terms)
Terms Based on Experimental Evidence (0 terms)
Terms Based on Predictions or Assertions (0 terms)
Biological Process (3 terms)
Terms Based on Experimental Evidence (3 terms)
CV Term
Evidence
References
involved_in apoptotic process
inferred from mutant phenotype
(Srinivasula et al., 2002, Wing et al., 2002)
inferred from genetic interaction with FLYBASE:grim; FB:FBgn0015946
(Srinivasula et al., 2002)
inferred from direct assay
(Christich et al., 2002)
inferred from genetic interaction with FLYBASE:rpr; FB:FBgn0011706
(Wing et al., 2002)
inferred from genetic interaction with FLYBASE:nanos; FB:FBgn0002962
(Sato et al., 2007)
involved_in cellular response to ionizing radiation
inferred from direct assay
(Christich et al., 2002)
involved_in programmed cell death involved in cell development
inferred from mutant phenotype
(Lee et al., 2013)
Terms Based on Predictions or Assertions (1 term)
CV Term
Evidence
References
involved_in apoptotic process
non-traceable author statement
(Holcik, 2002)
Cellular Component (1 term)
Terms Based on Experimental Evidence (0 terms)
Terms Based on Predictions or Assertions (0 terms)
Gene Group (FlyBase)
Protein Family (UniProt)
-
Protein Signatures (InterPro)
    -
    Summaries
    Gene Snapshot
    sickle (skl) encodes a member of the inhibitor of apoptotic protein antagonists. It is partially involved in the apoptosis of some larval neurons during metamorphosis. [Date last reviewed: 2019-03-14]
    Gene Group (FlyBase)
    RHG PROTEINS -
    RHG proteins possess a 12 amino acid RHG motif. This motif, also known as the IAP-binding motif (IBM), interacts with the BIR domain of Inhibitor of apoptosis proteins (IAPs) and relieving IAP-mediated caspase inhibition. Over-expression of individual RHG proteins is sufficient to induce apoptosis. (Adapted from FBrf0225510).
    Summary (Interactive Fly)

    novel apoptosis activator - contains an N-terminal inhibitor of apoptosis motif - partially involved in the apoptosis of some larval neurons during metamorphosis

    Gene Model and Products
    Number of Transcripts
    1
    Number of Unique Polypeptides
    1

    Please see the JBrowse view of Dmel\skl 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
    Structure
    Protein 3D structure   (Predicted by AlphaFold)   (AlphaFold entry Q9VVP8)

    If you don't see a structure in the viewer, refresh your browser.
    Model Confidence:
    • Very high (pLDDT > 90)
    • Confident (90 > pLDDT > 70)
    • Low (70 > pLDDT > 50)
    • Very low (pLDDT < 50)

    AlphaFold produces a per-residue confidence score (pLDDT) between 0 and 100. Some regions with low pLDDT may be unstructured in isolation.

    Experimentally Determined Structures
    Crossreferences
    Comments on Gene Model

    Gene model reviewed during 5.46

    Transcript Data
    Annotated Transcripts
    Name
    FlyBase ID
    RefSeq ID
    Length (nt)
    Assoc. CDS (aa)
    skl-RA
    FBtr0075119
    NM_079415
    1382
    108
    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
    UniProt
    RefSeq ID
    GenBank
    skl-PA
    FBpp0074885
    11.7
    108
    4.49
    Q9VVP8
    NP_524139
    AAF49263
    Polypeptides with Identical Sequences

    There is only one protein coding transcript and one polypeptide associated with this gene

    Additional Polypeptide Data and Comments
    Reported size (kDa)
    Comments
    External Data
    Crossreferences
    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\skl 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
    Testis-specificity index

    The testis specificity index was calculated from modENCODE tissue expression data by Vedelek et al., 2018 to indicate the degree of testis enrichment compared to other tissues. Scores range from -2.52 (underrepresented) to 5.2 (very high testis bias).

    -0.56

    Transcript Expression
    in situ
    Stage
    Tissue/Position (including subcellular localization)
    Reference
    embryonic stage
    embryonic/larval plasmatocyte | subset

    Comment: phagocytic macrophages

    (Wing et al., 2002)
    embryonic stage 7 -- 8
    hindgut anlage
    (Fisher et al., 2012)
    embryonic stage 9 -- 10
    antennal primordium

    Comment: reported as procephalic ectoderm primordium

    (Fisher et al., 2012)
    central brain primordium

    Comment: reported as procephalic ectoderm primordium

    (Fisher et al., 2012)
    visual primordium

    Comment: reported as procephalic ectoderm primordium

    (Fisher et al., 2012)
    dorsal head epidermis primordium

    Comment: reported as procephalic ectoderm primordium

    (Fisher et al., 2012)
    lateral head epidermis primordium

    Comment: reported as procephalic ectoderm primordium

    (Fisher et al., 2012)
    ventral head epidermis primordium

    Comment: reported as procephalic ectoderm primordium

    (Fisher et al., 2012)
    foregut primordium
    (Fisher et al., 2012)
    inclusive hindgut primordium
    (Fisher et al., 2012)
    embryonic stage 9 -- 11
    primordial germ cell
    (Sato et al., 2007)
    embryonic stage 11 -- 12
    embryonic head | anterior | dorsal | restricted

    Comment: Two symmetric cell clusters

    (Wing et al., 2002)
    embryonic head | anterior | restricted | ventral

    Comment: Two symmetric cell clusters

    (Wing et al., 2002)
    neurogenic region | restricted

    Comment: Clusters of cells

    (Wing et al., 2002)
    central brain primordium
    (Fisher et al., 2012)
    clypeo-labral primordium
    (Fisher et al., 2012)
    embryonic central brain glial cell
    (Fisher et al., 2012)
    embryonic optic lobe primordium
    (Fisher et al., 2012)
    foregut primordium
    (Fisher et al., 2012)
    gnathal primordium
    (Fisher et al., 2012)
    hindgut proper primordium
    (Fisher et al., 2012)
    larval lateral VNC glial cell
    (Fisher et al., 2012)
    embryonic stage 13 -- 14
    larval ventral nerve cord of embryonic abdominal segment
    (Zhai et al., 2010)
    embryonic stage 13 -- 16
    embryonic brain
    (Fisher et al., 2012)
    embryonic central brain glial cell
    (Fisher et al., 2012)
    embryonic central brain neuron
    (Fisher et al., 2012)
    larval nervous system
    (Fisher et al., 2012)
    larval lateral VNC glial cell
    (Fisher et al., 2012)
    larval ventral nerve cord
    (Fisher et al., 2012)
    embryonic optic lobe primordium
    (Fisher et al., 2012)
    embryonic inner optic lobe primordium
    (Fisher et al., 2012)
    embryonic stage 13 -- 17
    cell | subset of larval ventral nerve cord

    Comment: Clusters of cells

    (Wing et al., 2002)
    cell | subset of embryonic brain

    Comment: Clusters of cells

    (Wing et al., 2002)
    embryonic stage 15 -- 17
    larval neuroblast
    (Tan et al., 2011)
    larval central nervous system
    (Tan et al., 2011)
    Additional Descriptive Data

    skl expression is almost restricted to the embryonic CNS from stage 15. They are almost completely co-localized with grim transcripts and this includes many neuroblasts in the abdominal segments of the CNS.

    (Tan et al., 2011)

    After embryonic stage 13, skl expression is mainly restricted to the posterior region of the ventral nerve cord.

    (Zhai et al., 2010)

    skl expression is induced in pole cells by maternal Tao, but full induction is suppressed in nos+ pole cells.

    (Sato et al., 2007)

    skl transcripts are first detected at embryonic stage 11, in a pair of symmetric pair of cell clusters in the dorsal anterior region of the head. By stage 12, a second symmetric pair of skl-positive cell clusters appear on the ventral anterior region of the head. Additionally, skl-positive cell clusters are present in the neurogenic region. Clusters of skl-positive cells are observed in the embryonic brain and ventral nerve cord for the rest of embryogenesis. The overall pattern is similar to that of cells that are expected to die in the nervous system.

    (Wing et al., 2002)
    Marker for
     
    Subcellular Localization
    CV Term
    Polypeptide Expression
    Additional Descriptive Data
    Marker for
     
    Subcellular Localization
    CV Term
    Evidence
    References
    Expression Deduced from Reporters
    High-Throughput Expression Data
    Associated Tools

    JBrowse - Visual display of RNA-Seq signals

    View Dmel\skl in JBrowse
    RNA-Seq by Region - Search RNA-Seq expression levels by exon or genomic region
    Bulk Downloads
    RNA-Seq RPKM values for all genes
    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
    DRscDB - A single-cell RNA-seq resource for data mining and data comparison across species
    EMBL-EBI Single Cell Expression Atlas - Single cell expression across species
    FlyAtlas - Adult expression by tissue, using Affymetrix Dros2 array
    FlyAtlas2 - A Drosophila melanogaster expression atlas with RNA-Seq, miRNA-Seq and sex-specific data
    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) 9-10
    • Stages(s) 11-12
    • Stages(s) 13-16
    FlyBase Wiki
    Image Based Resources
    Alleles, Insertions, Transgenic Constructs, and Aberrations
    Classical and Insertion Alleles ( 8 )
    For All Classical and Insertion Alleles Show
     
    Other relevant insertions
    Transgenic Constructs ( 8 )
    For All Alleles Carried on Transgenic Constructs Show
    Transgenic constructs containing/affecting coding region of skl
    Transgenic constructs containing regulatory region of skl
    Aberrations (Deficiencies and Duplications) ( 4 )
    Variants
    Variant Molecular Consequences
    Alleles Representing Disease-Implicated Variants
    Phenotypes
    Orthologs
    Downloads
    Download All DIOPT Orthologs
    Human Orthologs (via DIOPT v9.1)
    Species\Gene Symbol
    Score
    Best Score
    Best Reverse Score
    Source
    Compara
    Domainoid
    eggNOG
    Hieranoid
    Homologene
    Inparanoid
    OMA
    OrthoDB
    OrthoFinder
    OrthoInspector
    orthoMCL
    Panther
    Phylome
    SonicParanoid
    Alignment
    Complementation?
    Transgene?
    Homo sapiens (Human) (0)
    Model Organism Orthologs (via DIOPT v9.1)
    Species\Gene Symbol
    Score
    Best Score
    Best Reverse Score
    Source
    Compara
    Domainoid
    eggNOG
    Hieranoid
    Homologene
    Inparanoid
    OMA
    OrthoDB
    OrthoFinder
    OrthoInspector
    orthoMCL
    Panther
    Phylome
    SonicParanoid
    Alignment
    Complementation?
    Transgene?
    Rattus norvegicus (Norway rat) (0)
    Mus musculus (laboratory mouse) (0)
    Xenopus tropicalis (Western clawed frog) (0)
    Danio rerio (Zebrafish) (0)
    Caenorhabditis elegans (Nematode, roundworm) (0)
    Anopheles gambiae (African malaria mosquito) (0)
    Arabidopsis thaliana (thale-cress) (0)
    Saccharomyces cerevisiae (Brewer's yeast) (0)
    Schizosaccharomyces pombe (Fission yeast) (0)
    Escherichia coli (enterobacterium) (0)
    Other Organism Orthologs (via OrthoDB)
    Data provided directly from OrthoDB:skl. Refer to their site for version information.
    Paralogs
    Downloads
    Download All DIOPT Paralogs
    Paralogs (via DIOPT v9.1)
    Human Disease Associations
    FlyBase Human Disease Model Reports
      Disease Ontology (DO) Annotations
      Models Based on Experimental Evidence ( 0 )
      Allele
      Disease
      Evidence
      References
      Potential Models Based on Orthology ( 0 )
      Human Ortholog
      Disease
      Evidence
      References
      Modifiers Based on Experimental Evidence ( 0 )
      Allele
      Disease
      Interaction
      References
      Disease Associations of Human Orthologs (via DIOPT v9.1 and OMIM)
      Note that ortholog calls supported by only 1 or 2 algorithms (DIOPT score < 3) are not shown.
      Homo sapiens (Human)
      Gene name
      Score
      OMIM
      OMIM Phenotype
      DO term
      Complementation?
      Transgene?
      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
      Summary of Genetic Interactions
      Interaction Browsers
      View in FlyBase Interactions Browser   View in MIST tool (external link)
      Please look at the allele data for full details of the genetic interactions
      Starting gene(s)
      Interaction type
      Interacting gene(s)
      Reference
      skl
      enhanceable
      grim
      (Srinivasula et al., 2002)
      nanos|skl
      suppressible
      hid
      (Sato et al., 2007)
      Starting gene(s)
      Interaction type
      Interacting gene(s)
      Reference
      grim::rpr
      enhanceable
      skl
      (Wing et al., 2002)
      nanos
      enhanceable
      skl
      (Sato et al., 2007)
      stwl
      suppressible
      skl
      (Brun et al., 2006)
      External Data
      Linkouts
      BioGRID - A database of protein and genetic interactions.
      DroID - A comprehensive database of gene and protein interactions.
      MIST (genetic) - An integrated Molecular Interaction Database
      MIST (protein-protein) - An integrated Molecular Interaction Database
      Pathways
      Signaling Pathways (FlyBase)
      Metabolic Pathways
      FlyBase
      External Links
      External Data
      Linkouts
      KEGG Pathways - A collection of manually drawn pathway maps representing knowledge of molecular interaction, reaction and relation networks.
      Class of Gene
      Genomic Location and Detailed Mapping Data
      Chromosome (arm)
      3L
      Recombination map
      3-45
      Cytogenetic map
      75C6-75C6
      Sequence location
      FlyBase Computed Cytological Location
      Cytogenetic map
      Evidence for location
      75C6-75C6
      Limits computationally determined from genome sequence between P{PZ}W05014 and P{lacW}l(3)j14E7j14E7
      Experimentally Determined Cytological Location
      Cytogenetic map
      Notes
      References
      Experimentally Determined Recombination Data
      Location

      3-45

      (FlyBase, 2016)

      3-41.7

      (Comeron et al., 2012)
      Left of (cM)
      Right of (cM)
      Notes
      Stocks and Reagents
      Stocks (36)
      Genomic Clones (19)
       

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

      cDNA Clones (15)
       

      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 JBrowse 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)
      BDGP DGC clones
      Other clones
      RNAi and Array Information
      Linkouts
      DRSC - Results frm RNAi screens
      Antibody Information
      Laboratory Generated Antibodies
       
      Commercially Available Antibodies
       
      Cell Line Information
      Publicly Available Cell Lines
       
        Other Stable Cell Lines
         
          Other Comments

          The presence of skl in the Skp complex suggests that, like morgue, it may target th for degradation by the SCF complex.

          (Giot et al., 2003)

          skl may be an IAP antagonist and a transducer of apoptotic damage signalling.

          (Christich et al., 2002)

          skl may act with other IAP-inhibitory proteins to regulate apoptosis during development.

          (Srinivasula et al., 2002)

          Replaced with paper/evidence-based annotation. ha140627.

          (Christich, 2001.9.7)
          Relationship to Other Genes
          Source for database merge of

          Source for merge of: skl BcDNA:RE14076

          (FlyBase, 1996-)
          Additional comments

          Source for merge of skl BcDNA:RE14076 was a shared cDNA ( date:030728 ).

          (FlyBase, 1996-)
          Nomenclature History
          Source for database identify of

          Source for identity of: meph CG13701

          (Christich, 2001.9.7)
          Nomenclature comments
          Etymology
          Synonyms and Secondary IDs (9)
          Reported As
          Symbol Synonym
          BcDNA:RE14076
          CG13701
          (Keleman et al., 2009.8.5, Perkins et al., 2009, Grieder et al., 2007, Christich et al., 2002, Srinivasula et al., 2002, Srinivasula et al., 2002, Wing et al., 2002)
          Skl
          (Eroglu and Derry, 2016, Arya and White, 2015, Abdelwahid et al., 2011, Bergmann, 2010, Kornbluth and White, 2005, Srinivasula, 2001.11.14)
          meph
          sickle
          (Ferguson et al., 2021)
          skl
          (Cruz et al., 2026, Yadav et al., 2025, Ewen-Campen and Perrimon, 2024, Jang et al., 2024, Chan et al., 2023, Baonza et al., 2022, Feng et al., 2022, Al L Abaquita et al., 2021, Khan et al., 2021, Pop et al., 2020, Hall et al., 2019, Meltzer et al., 2019, Gene Disruption Project members, 2018-, Verghese and Su, 2018, Chen et al., 2016, Steller et al., 2014.7.9, Lee et al., 2013, Lee et al., 2013, Link et al., 2013, Zhang and Cohen, 2013, Ge et al., 2012, Zhai et al., 2012, Tan et al., 2011, Truscott et al., 2011, Zhai et al., 2010, Xia and Holcik, 2009, Xu et al., 2009, Hou et al., 2008, Mehrotra et al., 2008, Miguel-Aliaga et al., 2008, Zhang et al., 2008, Akdemir et al., 2007, Grieder et al., 2007, Hueber et al., 2007, Peterson et al., 2007, Sato et al., 2007, Wichmann et al., 2006, Leaman et al., 2005, Zhou, 2005, Brodsky et al., 2004, Stanyon et al., 2004)
          veto
          (Holcik, 2002)
          Name Synonyms
          Sickle
          (Hounsell and Fan, 2021, Pinto-Teixeira et al., 2016, Denton and Kumar, 2015, Kuranaga, 2011, Li and Cadigan, 2008, Kuranaga and Miura, 2007, Adrain, 2006, Juhasz and Sass, 2005, Kornbluth and White, 2005, Yan et al., 2004, Srinivasula, 2001.11.14)
          mephisto
          sickle
          (Sproston et al., 2025, Paul et al., 2018, Cheng et al., 2016, Elenbaas et al., 2015, Lim et al., 2015, Merino et al., 2015, Zhang et al., 2015, Steller et al., 2014.7.9, Lee et al., 2013, Link et al., 2013, Zhang and Cohen, 2013, Lim et al., 2012, Zhai et al., 2012, Chen et al., 2011, Lin et al., 2011, Tan et al., 2011, Zhai et al., 2010, Xu et al., 2009, Mehrotra et al., 2008, Miguel-Aliaga et al., 2008, Montero et al., 2008, Tang et al., 2008, Zhang et al., 2008, Hueber et al., 2007, Liu et al., 2007, Mabuchi et al., 2007, Peterson et al., 2007, Sato et al., 2007, Vazquez-Pianzola et al., 2007, Brun et al., 2006, Choi et al., 2006, Brennecke et al., 2005, Chan et al., 2005, Zhou, 2005, Brodsky et al., 2004, Rehmsmeier et al., 2004)
          Secondary FlyBase IDs
          • FBgn0047166
          Datasets (0)
          Study focus (0)
          Experimental Role
          Project
          Project Type
          Title
          Study result (0)
          Result
          Result Type
          Title
          External Crossreferences and Linkouts ( 38 )
          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/GCRP - The gene-centric reference proteome (GCRP) provides a 1:1 mapping between genes and UniProt accessions in which a single 'canonical' isoform represents the product(s) of each protein-coding gene.
          UniProt/TrEMBL - Automatically annotated and unreviewed records of protein sequence and functional information
          Other crossreferences
          AlphaFold DB - AlphaFold provides open access to protein structure predictions for the human proteome and other key proteins of interest, to accelerate scientific research.
          BDGP expression data - Patterns of gene expression in Drosophila embryogenesis
          DRscDB - A single-cell RNA-seq resource for data mining and data comparison across species
          EMBL-EBI Single Cell Expression Atlas - Single cell expression across species
          FlyAtlas2 - A Drosophila melanogaster expression atlas with RNA-Seq, miRNA-Seq and sex-specific data
          FlyMine - An integrated database for Drosophila genomics
          KEGG Genes - Molecular building blocks of life in the genomic space.
          MARRVEL_MODEL - MARRVEL (model organism gene)
          Linkouts
          BioGRID - A database of protein and genetic interactions.
          Drosophila Genomics Resource Center - Drosophila Genomics Resource Center (DGRC) cDNA clones
          DroID - A comprehensive database of gene and protein interactions.
          DRSC - Results frm RNAi screens
          Eukaryotic Promoter Database - A collection of databases of experimentally validated promoters for selected model organisms.
          FlyAtlas - Adult expression by tissue, using Affymetrix Dros2 array
          FlyCyc Genes - Genes from a BioCyc PGDB for Dmel
          Fly-FISH - A database of Drosophila embryo and larvae mRNA localization patterns
          Flygut - An atlas of the Drosophila adult midgut
          Interactive Fly - A cyberspace guide to Drosophila development and metazoan evolution
          KEGG Pathways - A collection of manually drawn pathway maps representing knowledge of molecular interaction, reaction and relation networks.
          MIST (genetic) - An integrated Molecular Interaction Database
          MIST (protein-protein) - An integrated Molecular Interaction Database
          References (140)