RBP3 (Retinol Binding Protein 3)
Interphotoreceptor Retinoid-Binding Protein: Key Player in Visual Cycle and Retinal Health
Gene Information Card
| Symbol | RBP3 |
|---|---|
| Full Name | Retinol Binding Protein 3 |
| Gene Type | Protein coding |
| Chromosomal Location | 10q11.22 |
| NCBI Gene ID | 5949 ncbi.nlm.nih.gov/gene/5949 |
| Ensembl ID | ENSG00000165879 |
| UniProt ID | P10745 |
| OMIM ID | 180090 |
| HGNC ID | 9922 |
| Aliases | IRBP, RBP-3, RP66, interphotoreceptor retinoid-binding protein |
Description
RBP3 encodes the interphotoreceptor retinoid-binding protein (IRBP), a large glycoprotein secreted by photoreceptor cells and localized to the interphotoreceptor matrix. IRBP is essential for the transport of retinoids between the retinal pigment epithelium (RPE) and photoreceptors during the visual cycle, protecting retinoids from degradation and facilitating their proper delivery. Mutations in RBP3 are associated with autosomal recessive retinitis pigmentosa (RP66) and other retinal dystrophies.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Retinitis pigmentosa 66 (RP66) | Loss-of-function mutations in RBP3 disrupt retinoid transport, leading to photoreceptor degeneration. | OMIM #615233; ClinVar; PMID: 25525159 |
| Retinal dystrophy | Impaired IRBP function causes accumulation of toxic retinoid intermediates and progressive vision loss. | OMIM; PMID: 28492532 |
| Leber congenital amaurosis (rare association) | Biallelic RBP3 variants may contribute to severe early-onset retinal degeneration. | ClinVar; PMID: 28492532 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Retina | High (nTPM ~200) | High |
| Pineal gland | Moderate (nTPM ~15) | Medium |
| Testis | Low (nTPM ~2) | Low |
| Brain (cerebellum) | Very low (nTPM <1) | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| ARPE-19 (RPE cell line) | Low | Low expression; IRBP primarily in photoreceptors |
| Y79 (retinoblastoma cell line) | Moderate | Photoreceptor-like expression |
| WERI-Rb-1 (retinoblastoma cell line) | Moderate | Photoreceptor-like expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1070G>A (p.Arg357Gln) | Missense | Rare | Reduced retinoid binding affinity |
| c.2200C>T (p.Arg734*) | Nonsense | Rare | Premature truncation, loss of function |
| c.3040C>T (p.Arg1014Trp) | Missense | Rare | Impaired secretion and stability |
| c.1A>G (p.Met1?) | Start loss | Rare | Complete loss of protein |
Mutation functional classification
Loss of Function (LOF)
Most RBP3 mutations are loss-of-function, leading to reduced or absent IRBP, disrupting retinoid transport and causing photoreceptor death.
Gain of Function (GOF)
No gain-of-function mutations reported for RBP3.
Dominant Negative (DN)
No dominant-negative mechanisms described; RBP3-associated disease is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Retinoid cycle (visual cycle) – Reactome R-HSA-2453902
• Vitamin A and carotenoid metabolism – KEGG hsa00830
Protein Summary
IRBP is a 135 kDa glycoprotein composed of four homologous repeats, each containing a retinoid-binding domain. It is secreted by rod and cone photoreceptors into the interphotoreceptor matrix, where it shuttles all-trans-retinol and 11-cis-retinal between the RPE and photoreceptors. IRBP also protects retinoids from isomerization and oxidation, and may modulate immune responses in the retina. Its crystal structure reveals a hydrophobic pocket for retinoid binding.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| RBP3 Knockout HEK293 Cell Line | EDJ-KQ5641 | Human | 5949 | Details Get a Quote |
| RBP3 Knockout HeLa Cell Line | EDJ-KQ54301 | Human | 5949 | Details Get a Quote |
| RBP3 Knockout A-549 Cell Line | EDJ-KQ62796 | Human | 5949 | Details Get a Quote |
| RBP3 Knockout HCT 116 Cell Line | EDJ-KQ71261 | Human | 5949 | Details Get a Quote |
