Details for: OR51B5

Gene ID: 282763

Gene Type:  Protein-coding  - A gene that serves as a template for producing a messenger RNA (mRNA) molecule, which is then translated into a functional protein.

Symbol: OR51B5

Ensembl ID: ENSG00000167355

Description: olfactory receptor family 51 subfamily B member 5

Cell Significance Landscape

Associated with

Significant Cells

Cell Significance Index (CSI) scores for the chosen context(s)

  • astrocyte of the cerebral cortex CL0002605
    CSI 11.61
    rCSI 26.04%
    PRS 99.98
  • near-projecting glutamatergic cortical neuron CL4023012
    CSI 4.33
    rCSI 16.36%
    PRS 100
  • L6b glutamatergic cortical neuron CL4023038
    CSI 3.45
    rCSI 10.77%
    PRS 99.99
  • L5 extratelencephalic projecting glutamatergic cortical neuron CL4023041
    CSI 2.23
    rCSI 8.02%
    PRS 99.98
  • corticothalamic-projecting glutamatergic cortical neuron CL4023013
    CSI 2.1
    rCSI 12.39%
    PRS 99.99

Cell ID: Standard Cell Ontology term used for mapping and comparing cells across experiments. Ensures consistency in analyzing cellular functions across tissues.
Fold Change: Represents the ratio of the current Cell Significance Index to the Cell Significance Index Threshold, indicating how much the gene expression has changed compared to a baseline.
Cell Significance Index: Reflects how strongly a gene is expressed in this specific cell.

Cell ID: Standard Cell Ontology term used for mapping and comparing cells across experiments. Ensures consistency in analyzing cellular functions across tissues.
Fold Change: Represents the ratio of the current Cell Significance Index to the Cell Significance Index Threshold, indicating how much the gene expression has changed compared to a baseline.
Cell Significance Index: Reflects how strongly a gene is expressed in this cell type. Calculated using techniques like effect size estimation and bootstrapping for reliability.

Cell ID: Standard Cell Ontology term used for mapping and comparing cells across experiments. Ensures consistency in analyzing cellular functions across tissues.
Fold Change: Represents the ratio of the current Cell Significance Index to the Cell Significance Index Threshold, indicating how much the gene expression has changed compared to a baseline.
Cell Significance Index: Reflects how strongly a gene is expressed in this cell type. Calculated using techniques like effect size estimation and bootstrapping for reliability.
Network Configuration

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Legend:
  • Query Gene
  • Node Color (Target Cell CSI, relative to current network):
    • Very High
    • High
    • Medium
    • Low
    • Very Low
    • CSI N/A
  • Node Size: Proportional to Target Cell CSI magnitude
  • STRING PPI Edge
  • Shared Pathway Edge (ONTOLOGY)

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Other Information

This section provides additional information about the gene, including a description generated by an AI language model and details about associated proteins.

## Summary Analyzed for its expression specificity (CSI Z-SCORE), [OR51B5](/details-gene/282763) is an olfactory receptor with a canonical role in smell perception. The data suggest a potentially novel, non-olfactory function, as it is identified as a highly specific, albeit potentially sparse, marker for distinct cell populations within the central nervous system, including [astrocytes of the cerebral cortex](/details-cell/CL0002605) and various subtypes of glutamatergic neurons. This expression pattern suggests that its G protein-coupled receptor signaling activity may be co-opted for chemosensory or cell-cell recognition roles within the brain. ## Cellular Roles and Expression Landscape The primary function of [OR51B5](/details-gene/282763) is as an olfactory receptor involved in the perception of smell, a role established by foundational genomic studies ([PubMed: 11121057](https://pubmed.ncbi.nlm.nih.gov/11121057), [PubMed: 14983052](https://pubmed.ncbi.nlm.nih.gov/14983052)). However, an analysis of its expression specificity across a broad cellular landscape reveals a highly restricted, non-canonical pattern. Within the **Overall** context, [OR51B5](/details-gene/282763) is flagged as a top-ranking specific gene for several cell types in the cerebral cortex. These include glial cells, specifically the [astrocyte of the cerebral cortex](/details-cell/CL0002605), as well as multiple neuronal subtypes such as [near-projecting glutamatergic cortical neurons](/details-cell/CL4023012), [L6b glutamatergic cortical neurons](/details-cell/CL4023038), and [corticothalamic-projecting glutamatergic cortical neurons](/details-cell/CL4023013). The gene's potential as a uniquely distinguishing marker for these cell populations is strongly suggested by its maximal effect size (deltaVal: 1.00) and exceptional percentile rank (PRS: >99.9%). However, this interpretation requires caution, as the CSI (Z-SCORE) is 0.00 and the associated p-values are not statistically significant (p > 0.3). This combination of metrics is consistent with an expression pattern that is highly restricted to these cell types but may be present at very low levels or in only a small, sparse subset of cells within each annotated population. This suggests that [OR51B5](/details-gene/282763) is not a ubiquitously expressed gene in these cortical cells, but rather a marker for a potentially rare or specific functional state. ## Pathways and Molecular Function [OR51B5](/details-gene/282763) is functionally annotated as a G protein-coupled receptor with [olfactory receptor activity](/details-go/GO:0004984), primarily participating in the [olfactory signaling pathway](/details-reactome/R-HSA-381753) for the [detection of chemical stimulus involved in sensory perception of smell](/details-go/GO:0050911). Its protein product is localized to the [plasma membrane](/details-go/GO:0005886), consistent with its role as a cell-surface receptor. While these annotations reflect its well-understood role in the olfactory epithelium, its specific expression in cortical astrocytes and neurons points to a plausible exaptation of these molecular functions. The [G protein-coupled receptor signaling pathway](/details-go/GO:0007186) is a versatile mechanism used throughout the body. In the context of the cerebral cortex, it is possible that [OR51B5](/details-gene/282763) does not respond to odorants but instead detects endogenous ligands such as neurotransmitters, metabolites, or lipids, thereby modulating glial or neuronal activity in a manner distinct from its canonical sensory role. ## Research Directions The discovery of a canonically olfactory receptor with specific expression in cortical neurons and glia opens up several avenues for future research. A critical next step would be to perform comparative analyses in disease states, such as neurodegenerative or neuroinflammatory conditions, to see if its expression is altered. Based on its unexpected expression pattern, [OR51B5](/details-gene/282763) could represent a novel therapeutic target. If its activation on astrocytes or specific neuronal subtypes modulates key pathological processes, agonists or antagonists could offer a highly specific means of intervention with potentially minimal off-target effects. ### Testable Hypotheses 1. **Hypothesis: [OR51B5](/details-gene/282763) functions as an endogenous chemosensor on cortical astrocytes.** It is hypothesized that [OR51B5](/details-gene/282763) on [astrocytes of the cerebral cortex](/details-cell/CL0002605) detects specific brain metabolites or lipid signaling molecules (e.g., short-chain fatty acids or endocannabinoids) produced during synaptic activity or metabolic stress. Activation of the receptor could trigger downstream calcium signaling cascades, influencing astrocytic support functions or gliotransmission. * **Experimental Approach:** Utilize human iPSC-derived astrocyte cultures and express [OR51B5](/details-gene/282763) ectopically. Screen a library of endogenous brain metabolites using a functional readout such as a live-cell calcium indicator (e.g., GCaMP) or a cAMP biosensor to identify potential ligands. 2. **Hypothesis: [OR51B5](/details-gene/282763) is involved in cell-cell recognition and synaptic organization.** The specific expression of [OR51B5](/details-gene/282763) in distinct neuronal populations like [L6b glutamatergic cortical neurons](/details-cell/CL4023038) suggests a role in establishing or maintaining precise neural circuits. It may function as a cell-surface adhesion or recognition molecule that guides synaptic pairing between specific pre- and post-synaptic partners. * **Experimental Approach:** In a mouse model, use CRISPR-Cas9 to knock out *Or51b5* specifically in cortical projection neurons. Analyze the consequences on synaptic density, morphology, and connectivity using a combination of high-resolution microscopy (e.g., array tomography or expansion microscopy) and electrophysiological recordings from connected cell pairs. 3. **Hypothesis: Aberrant [OR51B5](/details-gene/282763) expression contributes to excitotoxicity in neurological disorders.** Under pathological conditions like ischemia or traumatic brain injury, the expression of [OR51B5](/details-gene/282763) may be upregulated in glutamatergic neurons. Its activation by damage-associated molecular patterns (DAMPs) released from injured cells could potentiate glutamate release or enhance postsynaptic NMDA receptor activity, thereby exacerbating excitotoxic cell death. * **Experimental Approach:** Induce an excitotoxic injury in primary cortical neuron-astrocyte co-cultures (e.g., via oxygen-glucose deprivation). Quantify [OR51B5](/details-gene/282763) transcript and protein levels using qPCR and immunocytochemistry. Then, use shRNA to knockdown [OR51B5](/details-gene/282763) and assess whether this intervention reduces neuronal cell death and markers of excitotoxicity.

Genular Protein ID: 1364097057

Symbol: O51B5_HUMAN

Name: Olfactory receptor 51B5

UniProtKB Accession Codes:

Q9H339 B2RN59

Database IDs:

AGR 1 AlphaFoldDB 1 Antibodypedia 1 Bgee 1 BioGRID 1 BioGRID-ORCS 1 BioMuta 1 CCDS 1 CDD 1 CTD 1 ChiTaRS 1 DMDM 1 DNASU 1 DisGeNET 1 EMBL 6 Ensembl 1 ExpressionAtlas 1 GO 5 Gene3D 1 GeneCards 1 GeneTree 1 GeneWiki 1 GenomeRNAi 1 HGNC 1 HOGENOM 1 HPA 1 InParanoid 1 IntAct 1 InterPro 4 KEGG 1 MANE-Select 1 NCBI Taxonomy 1 OMA 1 OpenTargets 1 OrthoDB 1 PANTHER 2 PRINTS 2 PRO 1 PROSITE 2 PathwayCommons 1 PaxDb 1 PeptideAtlas 1 Pfam 1 PharmGKB 1 Pharos 1 PhosphoSitePlus 1 PhylomeDB 1 Proteomes 1 RNAct 1 Reactome 2 RefSeq 1 SMR 1 STRING 1 SUPFAM 1 TreeFam 1 UCSC 1 VEuPathDB 1 eggNOG 1 iPTMnet 1 neXtProt 1

Citations:

PubMed ID: 11121057

Title: Comparative structural and functional analysis of the olfactory receptor genes flanking the human and mouse beta-globin gene clusters.

PubMed ID: 11121057

DOI: 10.1073/pnas.97.26.14560

PubMed ID: 16554811

Title: Human chromosome 11 DNA sequence and analysis including novel gene identification.

PubMed ID: 16554811

DOI: 10.1038/nature04632

PubMed ID: 15489334

Title: The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).

PubMed ID: 15489334

DOI: 10.1101/gr.2596504

PubMed ID: 14983052

Title: The human olfactory receptor gene family.

PubMed ID: 14983052

DOI: 10.1073/pnas.0307882100

Sequence Information:

  • Length: 312
  • Mass: 35241
  • Checksum: CC84A55EDED229C4
  • Sequence:
    • MSSSGSSHPF LLTGFPGLEE AHHWISVFFL FMYISILFGN GTLLLLIKED HNLHEPMYFF 
LAMLAATDLG LALTTMPTVL GVLWLDHREI GSAACFSQAY FIHSLSFLES GILLAMAYDR 
FIAICNPLRY TSVLTNTRVV KIGLGVLMRG FVSVVPPIRP LYFFLYCHSH VLSHAFCLHQ 
DVIKLACADT TFNRLYPAVL VVFIFVLDYL IIFISYVLIL KTVLSIASRE ERAKALITCV 
SHICCVLVFY VTVIGLSLIH RFGKQVPHIV HLIMSYAYFL FPPLMNPITY SVKTKQIQNA 
ILHLFTTHRI GT

Genular Protein ID: 1734083975

Symbol: Q05CQ2_HUMAN

Name: N/A

UniProtKB Accession Codes:

Q05CQ2

Database IDs:

ARBA 5 AlphaFoldDB 1 BioGRID-ORCS 1 CTD 1 DNASU 1 DisGeNET 1 EMBL 2 GO 3 Gene3D 1 InterPro 4 KEGG 1 NCBI Taxonomy 1 OrthoDB 1 PANTHER 2 PRINTS 2 PROSITE 3 PeptideAtlas 1 Pfam 1 RefSeq 1 RuleBase 2 SMR 1 SUPFAM 1

Citations:

PubMed ID: 15489334

Title: The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).

PubMed ID: 15489334

DOI: 10.1101/gr.2596504

Sequence Information:

  • Length: 204
  • Mass: 23046
  • Checksum: 23975DA1E25E4A11
  • Sequence:
    • MSSSGSSHPF LLTGFPGLEE AHHWISVFFL FMYISILFGN GTLLLLIKED HNLHEPMYFF 
LAMLAATDLG LALTTMPTVL GVLWLDHREI GSAACFSQAY FIHSLSFLES GILLAMAYDR 
FIAICNPLRY TSVLTNTRVV KIGLGVLMRG FVSVVPPIRP LYFFLYCHSH VLSHAFCLHQ 
DVIKLACADT TFNRQKKKKK KKKK