BiP - Binding Immunoglobulin Protein (GRP78)

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protein1140 wordssynced 2026-04-02

BiP - Binding Immunoglobulin Protein (GRP78)

<table class="infobox infobox-protein">
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<th class="infobox-header" colspan="2">BiP - Binding Immunoglobulin Protein (GRP78)</th>
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<td class="label">Symbol</td>
<td><strong>BIP</strong></td>
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<td class="label">Full Name</td>
<td>BiP - Binding Immunoglobulin (GRP78)</td>
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<td class="label">Type</td>
<td>Protein</td>
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<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/?query=BIP" target="_blank">Search UniProt</a></td>
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<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/anxiety" style="color:#ef9a9a">Anxiety</a>, <a href="/wiki/bipolar" style="color:#ef9a9a">Bipolar</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a></td>
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<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">160 edges</a></td>
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BiP - Binding Immunoglobulin Protein (GRP78)

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<div style="background-color: #d0e8f0; padding: 5px; font-weight: bold; text-align: center;">BiP / GRP78</div>
<div style="padding: 5px;">
<b>Full Name</b>: Binding Immunoglobulin Protein<br/>
<b>Also Known As</b>: GRP78, HSPA5, BiP<br/>
<b>Gene</b>: [HSPA5](/genes/hspa5)<br/>
<b>UniProt ID</b>: [P11021](https://www.uniprot.org/uniprot/P11021)<br/>
<b>Molecular Weight</b>: 78 kDa<br/>
<b>Subcellular Location</b>: Endoplasmic reticulum lumen<br/>
<b>PDB Structures</b>: [5E84](https://www.rcsb.org/structure/5E84), [3IUC](https://www.rcsb.org/structure/3IUC)<br/>
</div>
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Overview

Mermaid diagram (expand to render)

Binding Immunoglobulin Protein (BiP), also known as Glucose-Regulated Protein 78 (GRP78) or HSPA5, is the master endoplasmic reticulum (ER) chaperone and the central regulator of the [unfolded protein response](/mechanisms/endoplasmic-reticulum-stress) (UPR). BiP is an HSP70 family ATPase that binds to unfolded and misfolded proteins in the ER lumen, facilitating proper protein folding, assembly, and quality control.[@gething1992][@lee2005]

In neurodegenerative diseases, BiP serves as both a sensor of ER stress and a protective factor against protein aggregation. Changes in BiP expression and function are observed in [Alzheimer's disease](/diseases/alzheimers-disease), [Parkinson's disease](/diseases/parkinsons-disease), and [amyotrophic lateral sclerosis](/diseases/amyotrophic-lateral-sclerosis), making it a potential therapeutic target and biomarker.[@kimata2011]

Structure and Domains

BiP is composed of two major domains:

Nucleotide-Binding Domain (NBD): The N-terminal 44 kDa domain contains the ATPase activity. ATP binding and hydrolysis regulate the conformational changes that control substrate binding and release. Contains conserved Walker A and Walker B motifs.
Substrate-Binding Domain (SBD): The C-terminal 25 kDa domain binds to hydrophobic stretches on unfolded proteins. Comprises:
SBDβ: A β-sandwich that forms the peptide-binding pocket
SBDα: A helical lid that covers the bound substrate when ATP is hydrolyzed to ADP

The two domains are connected by a hydrophobic linker. ATP binding to the NBD triggers conformational changes that open the SBD, releasing the substrate. ATP hydrolysis closes the lid, trapping the substrate for folding.[@yang2018]

Co-Chaperones and Regulation

BiP function is regulated by ER-resident co-chaperones:

ERdj proteins (DNAJ homologs): Stimulate BiP ATPase activity (ERdj1-8)
BAP (BiP-Associated Protein): Nucleotide exchange factor that promotes ADP release
GRP170 (ORP150): Nucleotide exchange factor and holdase

Normal Function

Protein Folding and Quality Control

BiP performs essential functions in the ER:

De Novo Folding: Binds nascent polypeptide chains as they enter the ER via the Sec61 translocon

Oligomeric Assembly: Assists in multi-subunit protein assembly

ER-Associated Degradation (ERAD): Delivers terminally misfolded proteins to retrotranslocation channels

Calcium Buffering: Contributes to ER calcium storage capacity

Translocation Control: Seals the Sec61 translocon to prevent ion leakage[@wei1996]

UPR Sensor Regulation

BiP is the master regulator of all three [UPR](/entities/unfolded-protein-response) sensors:

[IRE1](/proteins/ire1): BiP binding keeps IRE1 monomeric and inactive. ER stress causes BiP release, allowing IRE1 dimerization and activation.
[PERK](/proteins/perk): Similarly regulated by BiP dissociation. PERK activation phosphorylates [eIF2α](/proteins/eif2a) to attenuate translation.
[ATF6](/proteins/atf6): BiP retains ATF6 in the ER. Upon stress, BiP release permits ATF6 trafficking to the Golgi for proteolytic activation.

This elegant mechanism ensures that the UPR is activated only when misfolded proteins accumulate and compete for BiP binding.[@bertolotti2000]

Role in Neurodegeneration

Alzheimer's Disease

In [Alzheimer's disease](/diseases/alzheimers-disease), BiP expression is increased in affected brain regions:

Amyloid-β Response: BiP upregulation occurs in [neurons](/entities/neurons) with [amyloid-β](/proteins/amyloid-beta) accumulation
[Tau](/proteins/tau) Interaction: BiP can interact with [tau](/proteins/tau) and may affect tau aggregation
Neuroprotection: BiP overexpression protects neurons against Aβ toxicity in cell and animal models
Synaptic Function: BiP modulates calcium homeostasis relevant to synaptic transmission[@hoozemans2005]

Post-mortem studies show elevated BiP immunoreactivity in AD [hippocampus](/brain-regions/hippocampus) and [cortex](/brain-regions/cortex), particularly in neurons containing neurofibrillary tangles.

Parkinson's Disease

In [Parkinson's disease](/diseases/parkinsons-disease):

α-Synuclein Aggregation: BiP interacts with [α-synuclein](/proteins/alpha-synuclein) and may influence aggregation kinetics
Dopaminergic Neurons: High BiP expression correlates with increased resistance to neurotoxins
LRRK2 Connection: Mutant [LRRK2](/proteins/lrrk2) may impair BiP function
MAM Localization: BiP is present at mitochondria-associated membranes affected in PD[@colla2012]

Amyotrophic Lateral Sclerosis

In [ALS](/diseases/amyotrophic-lateral-sclerosis):

SOD1 Mutants: Misfolded mutant [SOD1](/proteins/sod1) engages BiP and activates the UPR
[TDP-43](/mechanisms/tdp-43-proteinopathy): Cytoplasmic [TDP-43](/proteins/tdp-43) aggregates may sequester factors involved in BiP regulation
Motor Neuron Vulnerability: Motor neurons have limited BiP induction capacity

Huntington's Disease

In [Huntington's disease](/diseases/huntingtons):

PolyQ Expansion: Mutant [huntingtin](/proteins/huntingtin) with expanded polyglutamine tracts activates BiP expression
Aggregate Interaction: BiP can associate with huntingtin aggregates
Transcriptional Dysregulation: Mutant huntingtin may interfere with BiP gene induction[@thomas2010]

Therapeutic Targeting

Pharmacological Approaches

Chemical Chaperones: TUDCA, 4-PBA, and glycerol reduce the protein folding burden on BiP

BiP Inducers: Compounds that enhance BiP transcription through the UPR

BiP Stabilizers: Molecules that increase BiP protein stability or activity

Artemisinin Derivatives: Celastrol and other compounds upregulate BiP expression[@gupta2020]

Gene Therapy

AAV-BiP: Adeno-associated virus delivery of BiP to vulnerable neurons
Conditional Expression: Stress-inducible promoters for targeted BiP delivery

Cell Surface GRP78

In cancer, GRP78 can translocate to the cell surface and act as a signaling receptor. Similar phenomena may occur in stressed neurons, representing both a vulnerability and therapeutic opportunity.

Key Publications

[@gething1992]: Munro S, Pelham HR. [An Hsp70-like protein in the ER: identity with the 78 kd glucose-regulated protein and immunoglobulin heavy chain binding protein](https://doi.org/10.1016/0092-8674(86)90805-7). Cell. 1986;46(2):291-300.

[@lee2005]: Haas IG, Wabl M. [Immunoglobulin heavy chain binding protein](https://doi.org/10.1038/306387a0). Nature. 1983;306(5941):387-389.

[@kimata2011]: Hetz C, Saxena S. [The UPR: regulator of proteostasis, metabolism, and cell fate](https://doi.org/10.1038/s41580-017-0046-3). Nat Rev Mol Cell Biol. 2017;18(12):758-758.

[@yang2018]: Yang J, et al. [Conformational cycling of BiP](https://doi.org/10.1038/s41594-018-0168-x). Nat Struct Mol Biol. 2018;25(10):919-925.

[@wei1996]: Wei J, Hendershot LM. [Protein folding and assembly in the endoplasmic reticulum](https://doi.org/10.1016/0014-5793(96)00983-6). FEBS Lett. 1996;392(1):1-6.

[@bertolotti2000]: Bertolotti A, et al. [Dynamic interaction of BiP and ER stress transducers in the unfolded-protein response](https://doi.org/10.1038/35013000). Nat Cell Biol. 2000;2(6):326-332.

[@hoozemans2005]: Hoozemans JJ, et al. [The unfolded protein response is activated in Alzheimer's disease](https://doi.org/10.1002/ana.20005). Ann Neurol. 2005;58(3):467-473.

[@colla2012]: Colla E, et al. [Endoplasmic reticulum stress is important for the manifestations of α-synucleinopathy in vivo](https://doi.org/10.1523/JNEUROSCI.1642-12.2012). J Neurosci. 2012;32(10):3306-3320.

[@thomas2010]: Thomas M, et al. [Huntingtin's disease: protein-protein interactions and the unfolded protein response](https://doi.org/10.1016/j.nbd.2010.09.011). Neurobiol Dis. 2011;43(1):1-10.

[@gupta2020]: Gupta S, et al. [GRP78 (BiP) as a therapeutic target in neurodegenerative diseases](https://doi.org/10.1089/ars.2020.8169). Antioxid Redox Signal. 2021;35(11):839-859.

References

[Unknown, Gething & Sambrook, BiP (GRP78) molecular chaperone (1992) (1992)](https://doi.org/10.1038/355033a0)

[Lee et al., Role of BiP in ER stress and neurodegeneration (2005) (2005)](https://doi.org/10.1016/j.tibs.2005.09.001)

[Unknown, Kimata & Kohno, BiP and the unfolded protein response (2011) (2011)](https://doi.org/10.1016/j.tibs.2011.06.002)

[Yang J, et al, Conformational cycling of BiP (2018)](https://doi.org/10.1038/s41594-018-0168-x)

[Wei J, Hendershot LM, Protein folding and assembly in the endoplasmic reticulum (1996)](https://doi.org/10.1016/0014-5793(96)

[Bertolotti A, et al, Dynamic interaction of BiP and ER stress transducers in the unfolded-protein response (2000)](https://doi.org/10.1038/35013000)

[Hoozemans JJ, et al, The unfolded protein response is activated in Alzheimer's disease (2005)](https://doi.org/10.1002/ana.20005)

[Colla E, et al, Endoplasmic reticulum stress is important for the manifestations of α-synucleinopathy in vivo (2012)](https://doi.org/10.1523/JNEUROSCI.1642-12.2012)

[Thomas M, et al, Huntingtin's disease: protein-protein interactions and the unfolded protein response (2010)](https://doi.org/10.1016/j.nbd.2010.09.011)

[Gupta S, et al, GRP78 (BiP) as a therapeutic target in neurodegenerative diseases (2020)](https://doi.org/10.1089/ars.2020.8169)

Pathway Diagram

The following diagram shows the key molecular relationships involving BiP - Binding Immunoglobulin Protein (GRP78) discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

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BiP - Binding Immunoglobulin Protein (GRP78)

BiP - Binding Immunoglobulin Protein (GRP78)

BiP - Binding Immunoglobulin Protein (GRP78)

Overview

Structure and Domains

Co-Chaperones and Regulation

Normal Function

Protein Folding and Quality Control

UPR Sensor Regulation

Role in Neurodegeneration

Alzheimer's Disease

Parkinson's Disease

Amyotrophic Lateral Sclerosis

Huntington's Disease

Therapeutic Targeting

Pharmacological Approaches

Gene Therapy

Cell Surface GRP78

Key Publications

See Also

References

Pathway Diagram