IMPG1: Interphotoreceptor Matrix Proteoglycan 1
Key component of the interphotoreceptor matrix essential for retinal adhesion and photoreceptor survival
Gene Information Card
| Symbol | IMPG1 |
|---|---|
| Full Name | Interphotoreceptor Matrix Proteoglycan 1 |
| Gene Type | protein-coding |
| Chromosomal Location | 6q14.1 |
| NCBI Gene ID | 3617 ncbi.nlm.nih.gov/gene/3617 |
| Ensembl ID | ENSG00000112319 |
| UniProt ID | Q99727 |
| OMIM ID | 602870 |
| HGNC ID | 6049 |
| Aliases | IPM 150, SPACR, VMD2L1 |
Description
IMPG1 encodes interphotoreceptor matrix proteoglycan 1, a large chondroitin sulfate proteoglycan that is a major component of the interphotoreceptor matrix (IPM) in the retina. It plays a critical role in maintaining retinal adhesion, photoreceptor survival, and visual function by forming a structural scaffold between the retinal pigment epithelium and photoreceptor cells. Mutations in IMPG1 are associated with autosomal recessive vitelliform macular dystrophy and retinitis pigmentosa.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Vitelliform macular dystrophy (VMD) | Loss of IMPG1 disrupts IPM integrity, impairing retinal adhesion and leading to accumulation of lipofuscin-like material in the macula | ClinVar, OMIM |
| Retinitis pigmentosa (RP) | Defective IMPG1 compromises photoreceptor support, causing progressive rod-cone degeneration | ClinVar, OMIM |
| Macular dystrophy, patterned | Altered IPM composition due to IMPG1 mutations leads to patterned pigmentary changes in the macula | ClinVar |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Retina | 42.3 | High |
| Brain (cerebellum) | 1.2 | Low |
| Testis | 0.8 | Low |
| Heart | 0.5 | Not detected |
| Liver | 0.1 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| ARPE-19 (retinal pigment epithelium) | 15.6 | Moderate expression |
| Y79 (retinoblastoma) | 8.2 | Low expression |
| HEK293 (embryonic kidney) | 0.3 | Not detected |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1070G>A (p.Arg357Gln) | Missense | Rare | Alters proteoglycan structure, associated with VMD |
| c.1828C>T (p.Arg610Trp) | Missense | Rare | Disrupts IPM binding, linked to RP |
| c.2443delC (p.Leu815Trpfs*12) | Frameshift | Very rare | Loss of function, causes severe retinal dystrophy |
Mutation functional classification
Loss of Function (LOF)
Frameshift and nonsense mutations lead to truncated or absent IMPG1 protein, reducing IPM scaffold integrity and causing retinal degeneration.
Gain of Function (GOF)
No gain-of-function mutations reported for IMPG1.
Dominant Negative (DN)
Missense mutations may produce abnormal proteoglycan that interferes with wild-type IMPG1 function in the IPM, though evidence is limited.
View complete mutation data：
Gene Ontology (GO)
| • extracellular matrix structural constituent | • glycosaminoglycan binding |
| • extracellular space | • interphotoreceptor matrix |
| • visual perception | • retinal cell homeostasis |
Pathways
• Interphotoreceptor matrix organization
• Retinal adhesion and photoreceptor maintenance
Protein Summary
IMPG1 is a large chondroitin sulfate proteoglycan (approximately 150 kDa) secreted into the interphotoreceptor matrix. It contains multiple glycosaminoglycan attachment sites and a hyaluronan-binding domain, enabling it to form a hydrated matrix that stabilizes the interface between the retinal pigment epithelium and photoreceptor outer segments. This protein is essential for retinal adhesion, nutrient exchange, and photoreceptor survival.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| IMPG1 Knockout HEK293 Cell Line | EDJ-KQ4994 | Human | 3617 | Details Get a Quote |
| IMPG1 Knockout HeLa Cell Line | EDJ-KQ53657 | Human | 3617 | Details Get a Quote |
| IMPG1 Knockout A-549 Cell Line | EDJ-KQ62131 | Human | 3617 | Details Get a Quote |
| IMPG1 Knockout HCT 116 Cell Line | EDJ-KQ70621 | Human | 3617 | Details Get a Quote |
