Details for: ELSPBP1

Gene ID: 64100

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: ELSPBP1

Ensembl ID: ENSG00000169393

Description: epididymal sperm binding protein 1

Selected Context(s):  Overall

Cell Significance Landscape

Contexts:

Associated with

Significant Cells

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

  • OFF-bipolar cell CL0000750
    CSI 3.53
    rCSI 4.82%
    PRS 99.69
  • retinal rod cell CL0000604
    CSI 2.97
    rCSI 5.24%
    PRS 99.34

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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  • Node Color (Target Cell CSI, relative to current network):
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  • Node Size: Proportional to Target Cell CSI magnitude
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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 [ELSPBP1](/details-gene/64100) (Epididymal Sperm Binding Protein 1) is a protein-coding gene located on chromosome 19q13.33. As its name suggests, it is functionally annotated with roles in reproduction, specifically in processes like single fertilization ([GO:0007338](https://www.ebi.ac.uk/QuickGO/term/GO:0007338)) and sperm capacitation ([GO:0048240](https://www.ebi.ac.uk/QuickGO/term/GO:0048240)). It is known to be an extracellular, heparin-binding protein that localizes to the cell surface ([GO:0009986](https://www.ebi.ac.uk/QuickGO/term/GO:0009986)). Research has identified it as one of several sperm-binding proteins containing fibronectin type II-modules, suggesting a role in gamete interaction [[Link](https://doi.org/10.1002/1098-2795(200101)58:1<88::aid-mrd12>3.0.co;2-d)]. Intriguingly, expression data reveals its most significant cellular signatures are not in reproductive tissues but in the retina, particularly within [OFF-bipolar cell](/details-cell/CL0000750)s and [retinal rod cell](/details-cell/CL0000604)s, pointing towards a potentially novel and uncharacterized function in the visual system. ## Cellular Roles and Expression Landscape The expression profile of [ELSPBP1](/details-gene/64100) presents a notable dichotomy between its established functional annotation and its observed cellular significance. **Overall**, the gene demonstrates its highest significance in highly specialized neurons of the eye. Its most prominent expression is in [OFF-bipolar cell](/details-cell/CL0000750)s (CSI: 3.53), a type of retinal interneuron that transmits signals from photoreceptors. This is closely followed by high significance in [retinal rod cell](/details-cell/CL0000604)s (CSI: 2.97), the primary photoreceptors responsible for scotopic (low-light) vision. The strong and specific expression signature in these two interconnected cell types suggests a potential role for [ELSPBP1](/details-gene/64100) in photoreceptor maintenance, function, or the synaptic transmission between rod cells and bipolar cells. This pattern is unexpected given that the gene's discovery and characterization have been almost exclusively in the context of male reproductive biology [[Link](https://doi.org/10.1016/j.gene.2007.01.002)]. ## Pathways and Molecular Function The known molecular functions of [ELSPBP1](/details-gene/64100) are centered on its identity as a secreted, cell-surface-associated protein. Its annotation for heparin binding ([GO:0008201](https://www.ebi.ac.uk/QuickGO/term/GO:0008201)) is critical, as heparin-like molecules (heparan sulfate proteoglycans) are key components of the extracellular matrix and are involved in cell adhesion, signaling, and development in nearly all tissues, including the neural retina. This binding capability is consistent with its established role in sperm-egg interaction during fertilization ([GO:0007338](https://www.ebi.ac.uk/QuickGO/term/GO:0007338)). While its biological process annotations are specific to sperm capacitation ([GO:0048240](https://www.ebi.ac.uk/QuickGO/term/GO:0048240)) and fertilization, its molecular function as an extracellular binding protein could be repurposed in the retinal microenvironment. For instance, it may mediate interactions within the synaptic cleft or contribute to the structural integrity of the interphotoreceptor matrix that surrounds [retinal rod cell](/details-cell/CL0000604)s. ## Research Directions The striking discrepancy between the established reproductive function of [ELSPBP1](/details-gene/64100) and its highly specific expression in the retina opens up new avenues for investigation. The central research question is whether this retinal expression is functional or represents a biological artifact. ### Proposed Hypotheses 1. **[ELSPBP1](/details-gene/64100) is a synaptogenic or adhesion molecule in the outer retina.** Given its cell surface localization and heparin-binding ability, it may mediate the precise connection and signal transmission between [retinal rod cell](/details-cell/CL0000604)s and [OFF-bipolar cell](/details-cell/CL0000750)s, playing a role in the formation or maintenance of the first synapse in the visual pathway. 2. **[ELSPBP1](/details-gene/64100) contributes to the interphotoreceptor matrix (IPM).** As a secreted protein, it might be a component of the specialized extracellular matrix surrounding photoreceptors, where it could be involved in nutrient transport, waste clearance, or retinal adhesion, functions critical for photoreceptor survival. ### Key Experimental Approach To test the hypothesis that [ELSPBP1](/details-gene/64100) is a synaptic molecule, a combination of high-resolution imaging and functional analysis is required. Initially, expansion microscopy or stochastic optical reconstruction microscopy (STORM) combined with immunohistochemistry on retinal sections from wild-type mice could be used to determine if the ELSPBP1 protein co-localizes precisely with synaptic markers at the axon terminals of [retinal rod cell](/details-cell/CL0000604)s and the dendrites of [OFF-bipolar cell](/details-cell/CL0000750)s. Subsequently, generating a retina-specific conditional knockout of *Elspbp1* in mice would be the definitive experiment. Electroretinography (ERG) performed on these animals would reveal defects in the b-wave, which reflects bipolar cell activity, thereby providing functional evidence for a role in photoreceptor-to-bipolar cell signaling. ### Therapeutic Potential At present, the therapeutic potential of [ELSPBP1](/details-gene/64100) is highly speculative. However, if it proves essential for synaptic integrity or photoreceptor health, it could become a point of interest for retinal degenerative diseases. As a secreted, cell-surface protein, it is theoretically an accessible target for biologic therapies like therapeutic antibodies or recombinant protein replacement. Further research is required to determine if its dysregulation is associated with any pathology before its potential as a therapeutic target can be properly assessed.

Genular Protein ID: 3151611442

Symbol: ESPB1_HUMAN

Name: Epididymal sperm-binding protein 1

UniProtKB Accession Codes:

Q96BH3 Q96RT0 Q9H4C8

Database IDs:

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

Citations:

PubMed ID: 11144225

Title: Novel sperm-binding proteins of epididymal origin contain four fibronectin type II-modules.

PubMed ID: 11144225

DOI: 10.1002/1098-2795(200101)58:1&lt;88::aid-mrd12&gt;3.0.co;2-d

PubMed ID: 15057824

Title: The DNA sequence and biology of human chromosome 19.

PubMed ID: 15057824

DOI: 10.1038/nature02399

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: 17307309

Title: Sperm-binding fibronectin type II-module proteins are genetically linked and functionally related.

PubMed ID: 17307309

DOI: 10.1016/j.gene.2007.01.002

Sequence Information:

  • Length: 223
  • Mass: 26106
  • Checksum: FC7C215BA3E5CE51
  • Sequence:
    • MTRWSSYLLG WTTFLLYSYE SSGGMHEECV FPFTYKGSVY FTCTHIHSLS PWCATRAVYN 
GQWKYCQSED YPRCIFPFIY RGKAYNSCIS QGSFLGSLWC SVTSVFDEKQ QWKFCETNEY 
GGNSLRKPCI FPSIYRNNVV SDCMEDESNK LWCPTTENMD KDGKWSFCAD TRISALVPGF 
PCHFPFNYKN KNYFNCTNEG SKENLVWCAT SYNYDQDHTW VYC