PIGQ: Phosphatidylinositol Glycan Anchor Biosynthesis Class Q
Essential Component of GPI-Anchor Biosynthesis Pathway
Gene Information Card
| Symbol | PIGQ |
|---|---|
| Full Name | Phosphatidylinositol Glycan Anchor Biosynthesis Class Q |
| Gene Type | Protein coding |
| Chromosomal Location | 16p13.3 |
| NCBI Gene ID | 9091 ncbi.nlm.nih.gov/gene/9091 |
| Ensembl ID | ENSG00000107518 |
| UniProt ID | Q9BRB3 |
| OMIM ID | 605754 |
| HGNC ID | 8963 |
| Aliases | GPIBD9, PIG-Q, GPI1, MGC2650 |
Description
The PIGQ gene encodes a subunit of the GPI-N-acetylglucosaminyltransferase (GPI-GnT) complex, which catalyzes the first step in glycosylphosphatidylinositol (GPI) anchor biosynthesis. This complex transfers N-acetylglucosamine (GlcNAc) from UDP-GlcNAc to phosphatidylinositol (PI) on the cytoplasmic side of the endoplasmic reticulum. PIGQ is essential for the formation of GPI anchors, which tether proteins to the cell membrane. Mutations in PIGQ cause a congenital disorder of glycosylation (GPIBD9) characterized by intellectual disability, seizures, and dysmorphic features.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| GPI biosynthesis defect 9 (GPIBD9) | Loss-of-function mutations impair GPI anchor synthesis, reducing cell surface expression of GPI-anchored proteins. | OMIM #618548; multiple case reports with biallelic pathogenic variants |
| Early infantile epileptic encephalopathy | Disrupted GPI anchoring affects neuronal development and synaptic function. | ClinVar; literature reports of PIGQ variants in patients with seizures and developmental delay |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Brain | 8.2 | Low |
| Testis | 6.5 | Low |
| Kidney | 5.1 | Low |
| Liver | 4.8 | Low |
| Heart | 4.3 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 12.1 | Embryonic kidney cells; moderate expression |
| K562 | 9.8 | Lymphoblasts; moderate expression |
| HeLa | 7.5 | Cervical carcinoma; low 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 translation initiation; likely loss of function |
| c.337C>T (p.Arg113*) | Nonsense | Rare | Premature stop; loss of function |
| c.674G>A (p.Arg225Gln) | Missense | Rare | Impaired GPI-GnT complex activity; loss of function |
Mutation functional classification
Loss of Function (LOF)
Most reported PIGQ mutations are loss-of-function, leading to reduced GPI anchor synthesis and decreased cell surface GPI-APs.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative mutations reported; disease is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
| • GPI anchor biosynthetic process (GO:0006506) | • GPI-N-acetylglucosaminyltransferase complex (GO:0000506) |
| • Endoplasmic reticulum membrane (GO:0005789) | • transferring glycosyl groups (GO:0016757) |
Pathways
• GPI anchor biosynthesis (KEGG hsa00563)
• Metabolism of GPI-anchored proteins (Reactome R-HSA-162791)
Protein Summary
PIGQ is a 442-amino acid protein (UniProt Q9BRB3) that localizes to the endoplasmic reticulum membrane. It is a component of the GPI-N-acetylglucosaminyltransferase (GPI-GnT) complex, which includes PIGA, PIGC, PIGH, PIGP, PIGY, and DPM2. PIGQ is required for the transfer of GlcNAc to PI, the first committed step in GPI anchor biosynthesis. The protein has a single transmembrane domain and a luminal C-terminal region. Defects in PIGQ lead to reduced GPI anchor production, affecting the expression of numerous GPI-anchored proteins critical for cell signaling, adhesion, and immune function.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| PIGQ Knockout HEK293 Cell Line | EDJ-KQ6455 | Human | 9091 | Details Get a Quote |
| PIGQ Knockout A-549 Cell Line | EDJ-KQ30528 | Human | 9091 | Details Get a Quote |
| PIGQ Knockout HCT 116 Cell Line | EDJ-KQ30529 | Human | 9091 | Details Get a Quote |
| PIGQ Knockout HeLa Cell Line | EDJ-KQ30530 | Human | 9091 | Details Get a Quote |
