FB2026_01 , released March 12, 2026
FB2026_01 , released March 12, 2026
Gene: Dmel\Vm26Ab
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General Information
Symbol
Dmel\Vm26Ab
Species
D. melanogaster
Name
Vitelline membrane 26Ab
Annotation Symbol
CG9046
Feature Type
protein_coding_gene
FlyBase ID
FBgn0003980
Gene Model Status
Current
Stock Availability
9 publicly available
Gene Summary
Major early eggshell protein secreted by follicle cells into the perivitelline space and incorporated into the vitelline membrane (PubMed:3132408). Involved in vitelline membrane biogenesis; forms a cross-linked network with other vitelline membrane components (PubMed:15136154, PubMed:18514182, PubMed:20832396). (UniProt, P13238)
Contribute a Gene Snapshot for this gene.
All Summaries
Also Known As

sV23, VM26A.2, fs(2)QJ42, TU-4

Key Links
Genomic Location
Cytogenetic map
26A3-26A3
Sequence location
Recombination map
2-18
RefSeq locus
NT_033779 REGION:5957004..5957639
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 (5 terms)
Molecular Function (0 terms)
Terms Based on Experimental Evidence (0 terms)
Terms Based on Predictions or Assertions (0 terms)
Biological Process (4 terms)
Terms Based on Experimental Evidence (4 terms)
CV Term
Evidence
References
involved_in chorion-containing eggshell formation
inferred from high throughput mutant phenotype
(Schupbach and Wieschaus, 1991)
involved_in egg activation
inferred from mutant phenotype
(Tadros et al., 2003)
involved_in response to bacterium
inferred from high throughput expression pattern
(Levy et al., 2004)
involved_in vitelline membrane formation involved in chorion-containing eggshell formation
inferred from mutant phenotype
(Wu et al., 2010)
inferred from mutant phenotype
(Manogaran and Waring, 2004)
Terms Based on Predictions or Assertions (0 terms)
Cellular Component (1 term)
Terms Based on Experimental Evidence (1 term)
CV Term
Evidence
References
located_in vitelline envelope
inferred from physical interaction with FLYBASE:Vml; FB:FBgn0085362
(Wu et al., 2010)
inferred from direct assay
(Elalayli et al., 2008, Andrenacci et al., 2001)
Terms Based on Predictions or Assertions (0 terms)
Gene Group (FlyBase)
Protein Family (UniProt)
Belongs to the vitelline membrane protein family. (P13238)
Protein Signatures (InterPro)
Summaries
Gene Group (FlyBase)
VITELLINE MEMBRANE PROTEINS -
Vitelline membrane proteins encode structural components of the outer layer of the eggshell. They are characterized by a proline-rich domain and are synthesized during the early stages of eggshell formation. (Adapted from FBrf0205662 and FBrf0209278.)
Protein Function (UniProtKB)
Major early eggshell protein secreted by follicle cells into the perivitelline space and incorporated into the vitelline membrane (PubMed:3132408). Involved in vitelline membrane biogenesis; forms a cross-linked network with other vitelline membrane components (PubMed:15136154, PubMed:18514182, PubMed:20832396).
(UniProt, P13238)
Gene Model and Products
Number of Transcripts
2
Number of Unique Polypeptides
1

Please see the JBrowse view of Dmel\Vm26Ab 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 P13238)

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

Gene model reviewed during 5.56

Transcript Data
Annotated Transcripts
Name
FlyBase ID
RefSeq ID
Length (nt)
Assoc. CDS (aa)
Vm26Ab-RA
FBtr0079171
NM_057436
625
168
Vm26Ab-RB
FBtr0345439
NM_001298719
636
168
Additional Transcript Data and Comments
Reported size (kB)

0.7 (northern blot)

(Popodi et al., 1988)
Comments
External Data
Crossreferences
Polypeptide Data
Annotated Polypeptides
Name
FlyBase ID
Predicted MW (kDa)
Length (aa)
Theoretical pI
UniProt
RefSeq ID
GenBank
Vm26Ab-PA
FBpp0078802
16.8
168
8.00
P13238
NP_476784
AAF52308
Vm26Ab-PB
FBpp0311564
16.8
168
8.00
P13238
NP_001285648
AHN54163
Polypeptides with Identical Sequences

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

168 aa isoforms: Vm26Ab-PA, Vm26Ab-PB
Additional Polypeptide Data and Comments
Reported size (kDa)

168 (aa); 16.595 (kD predicted)

(Popodi et al., 1988)
Comments
External Data
Subunit Structure (UniProtKB)

Interacts with vml and Vm26Aa; forms part of a disulfide-linked network within the vitelline membrane of stage 10 egg chambers.

(UniProt, P13238)
Post Translational Modification

Proteolytically processed after secretion into the perivitelline space (PubMed:15136154). Undergoes several proteolytic processing steps during formation of the vitelline membrane; an initial processing step removing a C-terminal propeptide occurs between stage 9 and 12 of oogenesis while a second removing a N-terminal propeptide occurs between stage 11 and 14 (PubMed:15136154, PubMed:20832396).

Becomes part of a disulfide-linked network including other vitelline membrane proteins, including vml and Vm26Aa, during vitelline membrane biogenesis and maturation (PubMed:20832396). Cys-123, Cys-131 and Cys-140 are involved in disulfide network formation, with Cys-131 being the most important (PubMed:20832396). Undergoes both disulfide and non-disulfide cross-linking upon incorporation into the vitelline membrane (PubMed:18514182).

(UniProt, P13238)
Domain

The tetrapeptide (A-A-P-[AV]) repeats found throughout the protein are also present in many proteins constituting the protective envelope of other species.

The C-terminal propeptide is removed between stage 9 and 12 of oogenesis (PubMed:15136154). The C-terminal propeptide is non-essential for egg fertility (PubMed:15136154).

The N-terminal propeptide is removed between stage 11 and 14 of oogenesis (PubMed:15136154). The N-terminal propeptide is essential for egg fertility but its removal is not; may be involved in positioning and aligning this protein to facilitate disulfide and non-disulfide cross-linking within the vitelline membrane (PubMed:15136154).

The VM domain may be involved in facilitating efficient secretion of this protein.

(UniProt, P13238)
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\Vm26Ab 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).

-0.43

Transcript Expression
in situ
Stage
Tissue/Position (including subcellular localization)
Reference
oogenesis stage S10B
main body follicle cell
(Bernardi et al., 2006)
northern blot
Stage
Tissue/Position (including subcellular localization)
Reference
adult stage & oogenesis
follicle cell
(Popodi et al., 1988)
oogenesis stage S8 -- S11
(Popodi et al., 1988)
Additional Descriptive Data

Vm26Ab is expressed by all oocyte-associated follicle cells.

(Bernardi et al., 2006)

Vm26Ab is first detected in stage S8-S9 egg chambers, and persists until stage S11. Expression is follicle cell-specific.

(Popodi et al., 1988)
Marker for
 
Subcellular Localization
CV Term
Polypeptide Expression
immunolocalization
Stage
Tissue/Position (including subcellular localization)
Reference
oogenesis stage S10B
main body follicle cell
(Bernardi et al., 2006)
western blot
Stage
Tissue/Position (including subcellular localization)
Reference
embryonic stage
vitelline membrane
(Pascucci et al., 1996)
oogenesis stage S9 -- S14
(Pascucci et al., 1996)
Additional Descriptive Data

Vm26Ab is expressed by all oocyte-associated follicle cells.

(Bernardi et al., 2006)

The mobility of the Vm26Ab protein on Western blots shifts from a sharp 23 kD band at stage S9-S10A to a smear with a leading edge at 21 kD (up to stage S13) and later at 17 kD (stage S13-S14). In stage S10 egg chambers,Vm26Ab protein localizes to the vitelline membrane.

(Pascucci et al., 1996)
Marker for
 
Subcellular Localization
CV Term
Evidence
References
located_in vitelline envelope
inferred from physical interaction with FLYBASE:Vml; FB:FBgn0085362
(Wu et al., 2010)
inferred from direct assay
(Elalayli et al., 2008, Andrenacci et al., 2001)
Expression Deduced from Reporters
High-Throughput Expression Data
Associated Tools

JBrowse - Visual display of RNA-Seq signals

View Dmel\Vm26Ab 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
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
Flygut - An atlas of the Drosophila adult midgut
Images
FlyBase Wiki
Image Based Resources
Alleles, Insertions, Transgenic Constructs, and Aberrations
Classical and Insertion Alleles ( 3 )
For All Classical and Insertion Alleles Show
 
Other relevant insertions
Transgenic Constructs ( 19 )
For All Alleles Carried on Transgenic Constructs Show
Transgenic constructs containing/affecting coding region of Vm26Ab
Transgenic constructs containing regulatory region of Vm26Ab
Aberrations (Deficiencies and Duplications) ( 5 )
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:Vm26Ab. Refer to their site for version information.
Paralogs
Downloads
Download All DIOPT Paralogs
Paralogs (via DIOPT v9.1)
Gene Symbol
Score
Source
Compara
Domainoid
eggNOG
Homologene
Inparanoid
OMA
OrthoDB
OrthoFinder
OrthoInspector
orthoMCL
Panther
Phylome
SonicParanoid
Alignment
Drosophila melanogaster (Fruit fly) (6)
Vm34Ca
2 of 13
CG11585
1 of 13
Vm26Aa
1 of 13
Vm26Ac
1 of 13
Vm32E
1 of 13
Vml
1 of 13
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
    Starting gene(s)
    Interaction type
    Interacting gene(s)
    Reference
    Starting gene(s)
    Interaction type
    Interacting gene(s)
    Reference
    External Data
    Subunit Structure (UniProtKB)
    Interacts with vml and Vm26Aa; forms part of a disulfide-linked network within the vitelline membrane of stage 10 egg chambers.
    (UniProt, P13238 )
    Linkouts
    BioGRID - A database of protein and genetic interactions.
    DroID - A comprehensive database of gene and protein interactions.
    MIST (protein-protein) - An integrated Molecular Interaction Database
    Pathways
    Signaling Pathways (FlyBase)
    Metabolic Pathways
    FlyBase
    External Links
    External Data
    Linkouts
    Class of Gene
    Genomic Location and Detailed Mapping Data
    Chromosome (arm)
    2L
    Recombination map
    2-18
    Cytogenetic map
    26A3-26A3
    Sequence location
    FlyBase Computed Cytological Location
    Cytogenetic map
    Evidence for location
    26A3-26A3
    Limits computationally determined from genome sequence between P{EP}bchsEP2299&P{EP}GpdhEP466 and P{lacW}chick13321
    Experimentally Determined Cytological Location
    Cytogenetic map
    Notes
    References
    26A-26A
    (determined by in situ hybridisation)
    (Whiting et al., 1989, Burke et al., 1987)
    Experimentally Determined Recombination Data
    Location

    2-18

    (FlyBase, 2016)

    2-19.2

    (Comeron et al., 2012)
    Left of (cM)
    Right of (cM)
    Notes
    Stocks and Reagents
    Stocks (9)
    Genomic Clones (12)
     

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

    cDNA Clones (18)
     

    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
         

        polyclonal

        (Pascucci et al., 1996)
        Commercially Available Antibodies
         
        Cell Line Information
        Publicly Available Cell Lines
         
          Other Stable Cell Lines
           
            Other Comments

            In a sample of 79 genes with multiple introns, 33 showed significant heterogeneity in G+C content among introns of the same gene and significant positive correspondence between the intron and the third codon position G+C content within genes. These results are consistent with selection adding against preferred codons at the start of genes.

            (Kliman and Eyre-Walker, 1998)

            Polyclonal antibodies have been used to localise Vm26Aa, Vm26Ab, Cp18 and Cp36 in the assembly and mature eggshell. Vitelline membrane proteins are processed in a stage specific manner, morphological integrity of the outer chorion layers is dependent upon proper expression of at least one vitelline membrane component, sV23.

            (Pascucci et al., 1996)

            The Vm26Aa, Vm26Ab, Vm32E, Vm34Ca genes make up a multigene family that includes at least these four members.

            (Lindsley and Zimm, 1992)

            The Vm26Aa, Vm26Ab, Vm32E, Vm34Ca genes are responsible for encoding the major proteins of the first layer of the Drosophila eggshell, the vitelline membrane.

            (Lindsley and Zimm, 1992)

            Vm26Aa, Vm26Ab, Vm32E, Vm34Ca encode translation products with the high proline and alanine content characteristic of vitelline membrane proteins.

            (Gigliotti et al., 1989, Mindrinos et al., 1985)

            In situ hybridisation of recombinant DNA probes to polytene chromosomes of D.melanogaster and D.virilis is performed to study homologies between the chromosomal Muller elements of the two species.

            (Whiting et al., 1989)
            Relationship to Other Genes
            Source for database merge of
            Additional comments
            Nomenclature History
            Source for database identify of
            Nomenclature comments
            Etymology
            Synonyms and Secondary IDs (14)
            Reported As
            Symbol Synonym
            CG9046
            (National Institute of Genetics Fly Stocks, 2022-, Keleman et al., 2009.8.5, Perkins et al., 2009, Levy et al., 2004)
            DIM 29
            (Levy et al., 2004)
            Dm sV23
            (Fokta, 2001)
            Sv23
            (LeMosy and Hashimoto, 2000, Hong and Hashimoto, 1995)
            TU-4
            (Popodi et al., 1988)
            VM26A.2
            (Bernardi et al., 2009, Cavaliere et al., 2008, Bernardi et al., 2007, Bernardi et al., 2006, Andrenacci et al., 2001, Cernilogar et al., 2001)
            VM26AB
            (Norgate et al., 2007)
            Vm26A
            (Lin et al., 1993)
            Vm26Ab
            (Li et al., 2024, Sanderson et al., 2024, Gupta et al., 2022, National Institute of Genetics Fly Stocks, 2022-, York-Andersen et al., 2021, Ekhteraei-Tousi et al., 2020, Brown et al., 2014, Short and Lazzaro, 2013, Japanese National Institute of Genetics, 2012.5.21, Cernilogar et al., 2011, Wu et al., 2010, Baker and Russell, 2009, Zhang et al., 2009, Christensen et al., 2007.10.29, Jagadeeshan and Singh, 2007, Lai et al., 2007, Alatortsev, 2006, Christensen and Cook, 2006.8.29, Christensen and Cook, 2006.8.29, Stanyon et al., 2004)
            fs(2)QJ42
            (Andrenacci et al., 2001, Cernilogar et al., 2001, Pascucci et al., 1996)
            sV23
            (Zappia et al., 2011, Ventura et al., 2010, Wu et al., 2010, Elalayli et al., 2008, Wu and Waring, 2008, Fakhouri et al., 2006, Lee and Cooley, 2006, LeMosy et al., 2006, Schlichting et al., 2006, Greene and Waring, 2005, Wu and Waring, 2005, Manogaran and Waring, 2004, Waring et al., 2004, Manogaran et al., 2003, Manogaran et al., 2003, Anonymous, 2001, Heifetz et al., 2001, Manogaran et al., 2001, Trougakos et al., 2001, Fokta and Waring, 1997, Pascucci et al., 1996)
            sV26
            (Pascucci et al., 1996)
            sv23
            Name Synonyms
            Vitelline membrane 26Ab
            (McGraw et al., 2008)
            Secondary FlyBase IDs
              Datasets (0)
              Study focus (0)
              Experimental Role
              Project
              Project Type
              Title
              Study result (0)
              Result
              Result Type
              Title
              External Crossreferences and Linkouts ( 32 )
              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/Swiss-Prot - Manually annotated and reviewed records of protein sequence and functional information
              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.
              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
              InterPro - A database of protein families, domains and functional sites
              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
              Flygut - An atlas of the Drosophila adult midgut
              MIST (protein-protein) - An integrated Molecular Interaction Database
              References (88)