PIGS: Phosphatidylinositol Glycan Anchor Biosynthesis Class S
Essential subunit of the GPI transamidase complex involved in GPI anchor attachment
Gene Information Card
| Symbol | PIGS |
|---|---|
| Full Name | Phosphatidylinositol Glycan Anchor Biosynthesis Class S |
| Gene Type | protein-coding |
| Chromosomal Location | 17q24.3 |
| NCBI Gene ID | 94005 ncbi.nlm.nih.gov/gene/94005 |
| Ensembl ID | ENSG00000108384 |
| UniProt ID | Q96S52 |
| OMIM ID | 610274 |
| HGNC ID | 14937 |
| Aliases | GPI17, hGPI17, MGC26594 |
Description
PIGS encodes a subunit of the glycosylphosphatidylinositol (GPI) transamidase complex, which is essential for attaching GPI anchors to proteins. The GPI transamidase complex catalyzes the transfer of pre-assembled GPI anchors to nascent proteins in the endoplasmic reticulum. PIGS is required for complex stability and catalytic activity. Mutations in PIGS cause inherited GPI anchor deficiency with neurological features.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| GPI anchor deficiency (GPIBD) | Loss-of-function mutations impair GPI transamidase activity, reducing cell surface GPI-anchored proteins | OMIM #610274; multiple case reports |
| Intellectual disability, autosomal recessive | Disrupted GPI anchoring affects neuronal development and synaptic function | ClinVar; literature |
| Seizures, early-onset | GPI anchor deficiency leads to neuronal excitability and epilepsy | ClinVar; literature |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Brain | 12.5 | Medium |
| Liver | 8.3 | Low |
| Kidney | 10.1 | Medium |
| Heart | 9.7 | Medium |
| Lung | 7.4 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 14.2 | High expression |
| HeLa | 11.8 | Medium expression |
| K562 | 9.5 | Medium expression |
| SH-SY5Y | 13.0 | High expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | missense | Rare | Loss of start codon; likely loss of function |
| c.148C>T (p.Arg50*) | nonsense | Rare | Premature stop; loss of function |
| c.632G>A (p.Arg211Gln) | missense | Rare | Impaired complex assembly |
| c.1045C>T (p.Arg349Trp) | missense | Rare | Reduced GPI transamidase activity |
Mutation functional classification
Loss of Function (LOF)
Most reported PIGS mutations are loss-of-function, leading to reduced GPI-anchored protein levels.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative mutations reported; inheritance is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
| • GPI anchor biosynthetic process (GO:0006506) | • GPI-anchor transamidase activity (GO:0016255) |
| • endoplasmic reticulum membrane (GO:0005789) | • GPI-anchor transamidase complex (GO:0042765) |
Pathways
• GPI-anchor biosynthesis (KEGG: hsa00563)
• GPI-anchor transamidase complex (Reactome: R-HSA-162791)
Protein Summary
PIGS is a 60 kDa transmembrane protein localized to the endoplasmic reticulum. It is an essential component of the GPI transamidase complex, which also includes PIGK, PIGT, PIGU, and GPAA1. PIGS stabilizes the complex and is required for the cleavage of the GPI attachment signal peptide and the transfer of the GPI anchor to the protein. Deficiency leads to reduced cell surface expression of GPI-anchored proteins such as CD55 and CD59.
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