PIGX: Phosphatidylinositol Glycan Anchor Biosynthesis Class X
Essential component of the GPI-anchor transamidase complex involved in glycosylphosphatidylinositol (GPI) anchor attachment to proteins.
Gene Information Card
| Symbol | PIGX |
|---|---|
| Full Name | Phosphatidylinositol Glycan Anchor Biosynthesis Class X |
| Gene Type | Protein coding |
| Chromosomal Location | 3q29 |
| NCBI Gene ID | 151648 ncbi.nlm.nih.gov/gene/151648 |
| Ensembl ID | ENSG00000163904 |
| UniProt ID | Q8TBF5 |
| OMIM ID | 612908 |
| HGNC ID | 26039 |
| Aliases | GPIBD17, PIG-X, FLJ12884 |
Description
PIGX encodes a subunit of the glycosylphosphatidylinositol (GPI) transamidase complex, which is responsible for attaching GPI anchors to proteins in the endoplasmic reticulum. GPI-anchored proteins are involved in cell surface signaling, adhesion, and immune recognition. Mutations in PIGX cause GPI biosynthesis defect type 17 (GPIBD17), characterized by intellectual disability, seizures, and developmental delay.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| GPI biosynthesis defect type 17 (GPIBD17) | Loss-of-function mutations in PIGX impair GPI transamidase activity, reducing cell surface GPI-anchored protein expression. | OMIM #618010; ClinVar; PMID: 31216405 |
| Intellectual disability, autosomal recessive | Biallelic PIGX variants lead to neurodevelopmental phenotypes including global developmental delay and seizures. | OMIM #618010; PMID: 31216405 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Brain | 12.3 | Medium |
| Testis | 8.7 | Low |
| Lung | 6.2 | Low |
| Liver | 5.1 | Low |
| Kidney | 4.8 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 10.5 | Moderate expression |
| K562 | 7.3 | Low expression |
| HeLa | 6.9 | Low expression |
| SH-SY5Y | 11.1 | Moderate expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | Missense (start loss) | Rare | Loss of protein expression; associated with GPIBD17 |
| c.404G>A (p.Arg135Gln) | Missense | Rare | Impaired GPI transamidase activity |
| c.682C>T (p.Arg228*) | Nonsense | Rare | Premature truncation; loss of function |
Mutation functional classification
Loss of Function (LOF)
Biallelic loss-of-function mutations (nonsense, frameshift, start loss) reduce or abolish PIGX protein function, leading to GPI anchor deficiency.
Gain of Function (GOF)
No gain-of-function mutations reported for PIGX.
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) | • integral component of membrane (GO:0016021) |
Pathways
• GPI-anchor biosynthesis (Reactome: R-HSA-162791)
• Metabolism of proteins (Reactome: R-HSA-392499)
Protein Summary
PIGX is a 252-amino acid transmembrane protein localized to the endoplasmic reticulum. It forms part of the GPI transamidase complex (along with PIGK, PIGS, PIGT, and PIGU) that cleaves the GPI attachment signal peptide and transfers the preassembled GPI anchor to the C-terminus of target proteins. PIGX is essential for complex stability and catalytic activity.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| PIGX Knockout HEK293 Cell Line | EDJ-KQ14765 | Human | 54965 | Details Get a Quote |
| PIGX Knockout A-549 Cell Line | EDJ-KQ43917 | Human | 54965 | Details Get a Quote |
| PIGX Knockout HCT 116 Cell Line | EDJ-KQ45160 | Human | 54965 | Details Get a Quote |
| PIGX Knockout HeLa Cell Line | EDJ-KQ45161 | Human | 54965 | Details Get a Quote |
