FB2025_05 , released December 11, 2025
Gene: Dmel\PIG-S
Open Close
General Information
Symbol
Dmel\PIG-S
Species
D. melanogaster
Name
Phosphatidylinositol glycan anchor biosynthesis class S
Annotation Symbol
CG44255
Feature Type
protein_coding_gene
FlyBase ID
FBgn0265190
Gene Model Status
Current
Stock Availability
8 publicly available
Gene Summary
Phosphatidylinositol glycan anchor biosynthesis class S (PIG-S) encodes a subunit of the glycosylphosphatidylinositol (GPI) transamidase complex, which catalyzes the attachment of a preassembled GPI-anchor to the protein C-terminus in the endoplasmic reticulum lumen. GPI anchor attachment serves as a general mechanism for linking proteins to the cell surface membrane. [Date last reviewed: 2019-03-14] (FlyBase Gene Snapshot)
All Summaries
Key Links
Genomic Location
Cytogenetic map
96B6-96B6
Sequence location
Recombination map
3-86
RefSeq locus
NT_033777 REGION:24913216..24917864
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 (8 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 attachment of GPI anchor to protein
inferred from mutant phenotype
(Kawaguchi et al., 2019)
involved_in GPI anchored protein biosynthesis
inferred from mutant phenotype
(Satoh et al., 2013)
involved_in rhabdomere membrane biogenesis
inferred from mutant phenotype
(Satoh et al., 2013)
Terms Based on Predictions or Assertions (1 term)
CV Term
Evidence
References
involved_in attachment of GPI anchor to protein
inferred from biological aspect of ancestor with PANTHER:PTN000472159
(GO Reference Genome Project, 2011-)
inferred from electronic annotation with InterPro:IPR019540
(InterPro Project Members, 2004-)
Cellular Component (5 terms)
Terms Based on Experimental Evidence (5 terms)
CV Term
Evidence
References
located_in endomembrane system
inferred from high throughput direct assay
(Tan et al., 2009)
is_active_in endoplasmic reticulum membrane
inferred from direct assay
(Kawaguchi et al., 2021)
part_of GPI-anchor transamidase complex
inferred from direct assay
(Kawaguchi et al., 2021)
is_active_in nuclear membrane
inferred from direct assay
(Kawaguchi et al., 2021)
located_in nucleoplasm
inferred from high throughput direct assay
(Lye et al., 2014)
Terms Based on Predictions or Assertions (1 term)
CV Term
Evidence
References
part_of GPI-anchor transamidase complex
inferred from biological aspect of ancestor with PANTHER:PTN000472159
(GO Reference Genome Project, 2011-)
inferred from electronic annotation with InterPro:IPR019540
(InterPro Project Members, 2004-)
Gene Group (FlyBase)
Pathway (FlyBase)
Protein Family (UniProt)
-
Protein Signatures (InterPro)
Summaries
Gene Snapshot
Phosphatidylinositol glycan anchor biosynthesis class S (PIG-S) encodes a subunit of the glycosylphosphatidylinositol (GPI) transamidase complex, which catalyzes the attachment of a preassembled GPI-anchor to the protein C-terminus in the endoplasmic reticulum lumen. GPI anchor attachment serves as a general mechanism for linking proteins to the cell surface membrane. [Date last reviewed: 2019-03-14]
Gene Group (FlyBase)
GLYCOSYLPHOSPHATIDYLINOSITOL TRANSAMIDASE COMPLEX -
In glycosylphosphatidylinositol (GPI)-anchor biosynthesis, the GPI transamidase complex mediates GPI anchoring in the endoplasmic reticulum by replacing the protein's C-terminal GPI-attachment signal peptide with a preassembled GPI. (Adapted from PMID:11483512 and PMID:19883648).
PHOSPHATIDYLINOSITOL GLYCAN ANCHOR BIOSYNTHESIS GENES -
Phosphatidylinositol glycan anchor biosynthesis (PIG) genes, characterized extensively in humans, are involved in the synthesis of glycosylphosphatidylinositols (GPI) and their transfer to proteins to act as a lipid bilayer anchor. GPI is synthesized in the endoplasmic reticulum and is attached to the carboxyl terminus of a protein that has a GPI-attachment signal sequence. (Adapted from FBrf0220328, PMID:11102867 and PMID:19883648).
Pathway (FlyBase)
GPI-ANCHOR PROTEIN BIOSYNTHESIS -
The biosynthesis of glycosylphosphatidylinositol (GPI)-anchor proteins involves 3 steps: (1) the assembly of the GPI-anchor, which occurs in the endoplasmic reticulum (ER), and involves the sequential addition of a glucosamine, an acyl chain and 3 or 4 mannose residues (each modified with phosphoethanolamine, pEtn) to the inositol head group of phosphatidylinositol; (2) the attachment of the GPI-anchor to the protein carboxyl terminus via an amide bond to the last pEtn by the GPI transamidase complex; and (3) the post-attachment modifications of the GPI-anchor, which occur in the ER and Golgi apparatus and involve the removal of the 2nd mannose-linked pEtn and the inositol-linked acyl chain, followed by the remodeling of the fatty acid chains. The mature GPI-anchor proteins are transported to the plasma membrane. (Adapted from FBrf0220328 and PMID:32156170.)
Gene Model and Products
Number of Transcripts
1
Number of Unique Polypeptides
1

Please see the JBrowse view of Dmel\PIG-S 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 Q9VC10)

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

Genes with CDS overlap: isoforms of sud1 and PIG-S share promoter, first exon and N-terminal coding sequences (18 residues); overlapping structure not conserved outside of insects.

Gene model reviewed during 5.49

Transcript Data
Annotated Transcripts
Name
FlyBase ID
RefSeq ID
Length (nt)
Assoc. CDS (aa)
PIG-S-RC
FBtr0339112
NM_170181
1764
536
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
PIG-S-PC
FBpp0308257
60.4
536
7.82
Q9VC10
NP_733060
AAF56366
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
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\PIG-S 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).

3.48

Transcript Expression
in situ
Stage
Tissue/Position (including subcellular localization)
Reference
embryonic stage 1 -- 3
organism

Comment: maternally deposited

(Fisher et al., 2012)
embryonic stage 11 -- 12
anterior midgut primordium
(Fisher et al., 2012)
posterior midgut primordium
(Fisher et al., 2012)
embryonic stage 13 -- 16
embryonic/larval midgut
(Fisher et al., 2012)
Additional Descriptive Data
Marker for
 
Subcellular Localization
CV Term
Polypeptide Expression
mass spectroscopy
Stage
Tissue/Position (including subcellular localization)
Reference
adult stage
adult head
(Aradska et al., 2015)
day 5 of adulthood | male -- day 7 of adulthood | male
spermatozoon
(Dorus et al., 2006)
Additional Descriptive Data
Marker for
 
Subcellular Localization
CV Term
Evidence
References
located_in endomembrane system
inferred from high throughput direct assay
(Tan et al., 2009)
is_active_in endoplasmic reticulum membrane
inferred from direct assay
(Kawaguchi et al., 2021)
part_of GPI-anchor transamidase complex
inferred from direct assay
(Kawaguchi et al., 2021)
is_active_in nuclear membrane
inferred from direct assay
(Kawaguchi et al., 2021)
located_in nucleoplasm
inferred from high throughput direct assay
(Lye et al., 2014)
Expression Deduced from Reporters
High-Throughput Expression Data
Associated Tools

JBrowse - Visual display of RNA-Seq signals

View Dmel\PIG-S 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
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
Images
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 ( 3 )
For All Alleles Carried on Transgenic Constructs Show
Transgenic constructs containing/affecting coding region of PIG-S
Transgenic constructs containing regulatory region of PIG-S
Aberrations (Deficiencies and Duplications) ( 0 )
Inferred from experimentation ( 0 )
Inferred from location ( 5 )
Variants
Variant Molecular Consequences
Alleles Representing Disease-Implicated Variants
Phenotypes
For more details about a specific phenotype click on the relevant allele symbol.
Lethality
Allele
lethal - all die during embryonic stage
Phenotype manifest in
Allele
rhabdomere | somatic clone
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) (1)
Hsap\PIGS
13 of 14
Yes
Yes
1  
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) (1)
Rnor\Pigs
13 of 14
Yes
Yes
Mus musculus (laboratory mouse) (1)
Mmus\Pigs
12 of 14
Yes
Yes
Xenopus tropicalis (Western clawed frog) (2)
Xtro\pigs
11 of 13
Yes
Yes
Xtro\ldlr
1 of 13
No
No
Danio rerio (Zebrafish) (1)
Drer\pigs
13 of 14
Yes
Yes
Caenorhabditis elegans (Nematode, roundworm) (1)
Cele\pigs-1
12 of 14
Yes
Yes
Anopheles gambiae (African malaria mosquito) (1)
Agam\AgaP_AGAP002933
11 of 12
Yes
Yes
Arabidopsis thaliana (thale-cress) (1)
Atha\AT3G07180
11 of 13
Yes
Yes
Saccharomyces cerevisiae (Brewer's yeast) (1)
Scer\GPI17
11 of 13
Yes
Yes
Schizosaccharomyces pombe (Fission yeast) (1)
Spom\gpi17
9 of 12
Yes
Yes
Escherichia coli (enterobacterium) (0)
Other Organism Orthologs (via OrthoDB)
Data provided directly from OrthoDB:PIG-S. 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 ( 1 )
    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?
    PIGS; phosphatidylinositol glycan anchor biosynthesis class S
    13 of 14
    610271
     
    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
    Starting gene(s)
    Interaction type
    Interacting gene(s)
    Reference
    PIG-A
    enhanceable
    PIG-S
    (Thorpe et al., 2025)
    External Data
    Linkouts
    MIST (protein-protein) - An integrated Molecular Interaction Database
    Pathways
    Signaling Pathways (FlyBase)
    Metabolic Pathways
    FlyBase
    GPI-ANCHOR PROTEIN BIOSYNTHESIS
    External Links
    KEGG Metabolic Pathways - A collection of manually drawn metabolic pathway maps representing knowledge of molecular interaction, reaction and relation networks.
    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)
    3R
    Recombination map
    3-86
    Cytogenetic map
    96B6-96B6
    Sequence location
    FlyBase Computed Cytological Location
    Cytogenetic map
    Evidence for location
    96B6-96B6
    Experimentally Determined Cytological Location
    Cytogenetic map
    Notes
    References
    Experimentally Determined Recombination Data
    Location

    3-86

    (FlyBase, 2016)

    3-85.1

    (Comeron et al., 2012)
    Left of (cM)
    Right of (cM)
    Notes
    Stocks and Reagents
    Stocks (8)
    Genomic Clones (13)
     

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

    cDNA Clones (14)
     

    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
    Antibody Information
    Laboratory Generated Antibodies
     

    polyclonal

    (Kawaguchi et al., 2019)
    Commercially Available Antibodies
     
    Cell Line Information
    Publicly Available Cell Lines
     
      Other Stable Cell Lines
       
        Other Comments
        Relationship to Other Genes
        Source for database merge of
        Additional comments

        Annotation CG31120 split into CG44254 and CG44255 in release 5.49 of the genome annotation. The two annotations share a common 5' exon which encodes 18 N-terminal amino acid residues, but otherwise encode two distinct proteins.

        (FlyBase Genome Annotators, 2012)

        Annotations CG13644, CG6031, CG18761 merged as CG31120 in release 3 of the genome annotation.

        (FlyBase Genome Annotators, 2002-2003)
        Nomenclature History
        Source for database identify of
        Nomenclature comments
        Etymology

        Named "PIG-S" after the human ortholog.

        (FlyBase, 2009-)
        Synonyms and Secondary IDs (10)
        Reported As
        Symbol Synonym
        CG13644
        (Çiçek et al., 2016)
        CG31120
        (Aradska et al., 2015, Satoh et al., 2013, Japanese National Institute of Genetics, 2012.5.21, Kong et al., 2010, Keleman et al., 2009.8.5, Tan et al., 2009, Dorus et al., 2006)
        CG44255
        (Çiçek et al., 2016)
        CG6031
        PIG-S
        (Palermo et al., 2023, Dalton et al., 2022, Kawaguchi et al., 2019, Gene Disruption Project members, 2018-, Satoh et al., 2013)
        PIGS
        (Kawaguchi et al., 2021)
        sud2
        (Katz et al., 2014)
        Name Synonyms
        Phosphatidylinositol glycan anchor biosynthesis class S
        Phosphatidylinositol glycan anchor biosynthesis, class S
        Phosphatidylinositol glycan anchor biosynthesis, class S ortholog
        Secondary FlyBase IDs
        • FBgn0051120
        • FBgn0039247
        • FBgn0039248
        Datasets (0)
        Study focus (0)
        Experimental Role
        Project
        Project Type
        Title
        Study result (0)
        Result
        Result Type
        Title
        External Crossreferences and Linkouts ( 25 )
        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.
        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
        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
        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.
        FlyCyc Genes - Genes from a BioCyc PGDB for Dmel
        Fly-FISH - A database of Drosophila embryo and larvae mRNA localization patterns
        iBeetle-Base - RNAi phenotypes in the red flour beetle (Tribolium castaneum)
        KEGG Metabolic Pathways - A collection of manually drawn metabolic pathway maps representing knowledge of molecular interaction, reaction and relation networks.
        KEGG Pathways - A collection of manually drawn pathway maps representing knowledge of molecular interaction, reaction and relation networks.
        MIST (protein-protein) - An integrated Molecular Interaction Database
        References (36)