GP9 (Glycoprotein IX Platelet)
Platelet Glycoprotein IX Gene: Role in Hemostasis and Bernard-Soulier Syndrome
Gene Information Card
| Symbol | GP9 |
|---|---|
| Full Name | Glycoprotein IX Platelet |
| Gene Type | Protein coding |
| Chromosomal Location | 3q21.3 |
| NCBI Gene ID | 2815 ncbi.nlm.nih.gov/gene/2815 |
| Ensembl ID | ENSG00000169764 |
| UniProt ID | P14770 |
| OMIM ID | 173515 |
| HGNC ID | 4444 |
| Aliases | CD42a, GPIX |
Description
The GP9 gene encodes glycoprotein IX (GPIX), a small membrane protein that forms a non-covalent complex with glycoprotein Ib (GPIb) and glycoprotein V (GPV) on the platelet surface. This complex, known as the GPIb-IX-V receptor, is essential for platelet adhesion to von Willebrand factor (vWF) at sites of vascular injury. GPIX is required for the proper expression and function of the receptor complex. Mutations in GP9 cause Bernard-Soulier syndrome (BSS), a rare autosomal recessive bleeding disorder characterized by thrombocytopenia, giant platelets, and defective platelet adhesion.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Bernard-Soulier syndrome | Loss-of-function mutations in GP9 impair GPIb-IX-V complex assembly, reducing platelet adhesion to vWF and causing bleeding tendency. | ClinVar, OMIM #173515 |
| Platelet-type bleeding disorder 9 | Homozygous or compound heterozygous GP9 mutations lead to BSS phenotype. | OMIM #231200 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Whole blood | 12.7 | Low |
| Bone marrow | 5.2 | Low |
| Spleen | 2.1 | Not detected |
| Lung | 1.8 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| Megakaryocytes | -- | High expression expected; GP9 is platelet-specific |
| HEL (erythroleukemia) | -- | Expressed; used in platelet research |
| K562 | -- | Not expressed |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.182A>G (p.Asn61Ser) | Missense | Rare | Loss of function; disrupts GPIb-IX-V complex |
| c.70C>T (p.Arg24*) | Nonsense | Rare | Premature stop; loss of function |
| c.97G>A (p.Gly33Arg) | Missense | Rare | Loss of function; impairs surface expression |
Mutation functional classification
Loss of Function (LOF)
Most GP9 mutations are loss-of-function, leading to reduced or absent GPIX protein and defective GPIb-IX-V receptor complex.
Gain of Function (GOF)
No gain-of-function mutations reported for GP9.
Dominant Negative (DN)
No dominant-negative mutations reported; BSS is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
| • protein binding (GO:0005515) | • plasma membrane (GO:0005886) |
| • integral component of membrane (GO:0016021) | • platelet alpha granule lumen (GO:0031093) |
| • neuromedin U binding (GO:0031594) | • extracellular exosome (GO:0070062) |
Pathways
• Platelet adhesion to exposed collagen (Reactome: R-HSA-76009)
• GPIb-IX-V activation signalling (Reactome: R-HSA-430116)
Protein Summary
Glycoprotein IX (GPIX) is a 177-amino acid transmembrane protein with a single leucine-rich repeat domain. It is expressed exclusively on platelets and megakaryocytes. GPIX associates with GPIbα and GPIbβ (encoded by GP1BA and GP1BB) and GPV (GP5) to form the GPIb-IX-V complex. This complex binds von Willebrand factor (vWF) exposed at sites of vascular injury, initiating platelet adhesion and activation. GPIX is essential for the stability and surface expression of the entire complex. Defects in GPIX cause Bernard-Soulier syndrome.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| GP9 Knockout HEK293 Cell Line | EDJ-KQ4745 | Human | 2815 | Details Get a Quote |
| GP9 Knockout HeLa Cell Line | EDJ-KQ53380 | Human | 2815 | Details Get a Quote |
| GP9 Knockout A-549 Cell Line | EDJ-KQ61856 | Human | 2815 | Details Get a Quote |
| GP9 Knockout HCT 116 Cell Line | EDJ-KQ70341 | Human | 2815 | Details Get a Quote |
