<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">RALB Protein — RAS-Related Protein Ral-B</th>
</tr>
<tr> [@ral2012]
<td class="label">Gene</td> [@ralb2018]
<td>[RALB](/genes/ralb)</td> [@ral2019]
</tr> [@ralb2019]
<tr> [@ralb2013]
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/P11234" target="_blank">P11234</a></td>
</tr>
<tr>
<td class="label">PDB Structures</td>
<td><a href="https://www.rcsb.org/structure/1U2X" target="_blank">1U2X</a>, <a href="https://www.rcsb.org/structure/2KWI" target="_blank">2KWI</a>, <a href="https://www.rcsb.org/structure/1MS9" target="_blank">1MS9</a></td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~23 kDa</td>
</tr>
<tr>
<td class="label">Length</td>
<td>206 amino acids</td>
</tr>
<tr>
<td class="label">Subcellular Localization</td>
<td>Cytoplasm, Plasma membrane, Vesicles, Synapses</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>RAS GTPase family, Ral subfamily</td>
</tr>
<tr>
<td class="label">Aliases</td>
<td>Ras-related protein Ral-B, Ral-B</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">17 edges</a></td>
</tr>
</table>
Introduction
Ralb Protein Ras Related Protein Ral B is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Overview
RALB (RAS-Related Protein Ral-B) is a small GTPase belonging to the Ras superfamily of monomeric G proteins [@ral2011]. The 206-amino acid protein functions as a molecular switch, cycling between an active GTP-bound state and an inactive GDP-bound state to regulate diverse cellular processes including vesicle trafficking, actin dynamics, cell proliferation, and immune function [@ral2008].
RALB is one of two Ral proteins (RALA and RALB) that share approximately 50% homology with Ras proteins but have distinct cellular functions [@rala2010]. RALB has emerged as an important player in neurodegenerative diseases, particularly Alzheimer's and Parkinson's Disease, through its roles in amyloid processing, synaptic function, and mitochondrial dynamics.
Structure
GTPase Domain Architecture
Like other small GTPases, RALB has a characteristic fold [@structure2004]:
N-terminus
|
GxxxxGKST ---- Switch I ---- Switch II ---- GxxxxGKST
P-loop GTP binding GTP hydrolysis
|
C-terminus (CAAX motif: CQLN)
Key Structural Features
| Feature | Description |
|---------|-------------|
| GxxxxGKST (P-loop) | Nucleotide binding (positions 20-25) |
| Switch I | Conformational change on GTP/GDP (positions 35-45) |
| Switch II | GTP hydrolysis (positions 60-75) |
| CAAX motif | CQLN — prenylation for membrane localization |
Nucleotide Binding
| State | Conformation | Effectors Bound |
|-------|--------------|----------------|
| GTP | Active | Ral effectors (exocyst, RalBP1, etc.) |
| GDP | Inactive | No effectors |
| GDP+Pi | Transition | Intermediate |
Normal Function
Molecular Switch Cycle
RALB cycles between active and inactive states [@ral2008]:
GDP-RALB + GEF → GDP release → RALB-GTP + effectors
↓
GAPs
↓
GTP hydrolysis
↓
GDP-RALB + Pi
↓
GDIs
↓
Cytosolic pool
Regulation
| Regulator | Function | Examples |
|-----------|----------|----------|
| GEFs | Activate (GTP binding) | RALGDS, RGL, RGL3 |
| GAPs | Inactivate (GTP hydrolysis) | RALGAPs |
| GDIs | Extract from membranes | RHOGDI |
Key Cellular Pathways
1. Vesicle Trafficking
RALB controls vesicular transport [@ral2012]:
- Exocyst-mediated exocytosis — RALB-exocyst interaction tethers vesicles to plasma membrane
- Endocytosis — regulates early endosome function
- [Autophagy](/entities/autophagy) — essential for autophagosome formation
- Synaptic vesicle release — controls neurotransmitter release
2. Cytoskeletal Dynamics
- Actin stress fiber formation
- Membrane ruffling
- Cell migration
- Cytokinesis
3. Cell Survival and Proliferation
- MAPK/ERK pathway activation
- PI3K/AKT signaling
- Cell cycle progression
4. Immune Function
- T-cell receptor signaling
- B-cell activation
- Cytokine production
Brain Functions
In [neurons](/entities/neurons), RALB is particularly important for [@ralb2018]:
- Synaptic vesicle trafficking
- Dendritic spine morphology
- Axonal growth
- Membrane protein trafficking
Role in Disease
Alzheimer's Disease
RALB is implicated in AD through multiple mechanisms [@ralb2018][@ral2019]:
Amyloid Processing
- Regulates [APP](/entities/app-protein) trafficking through secretory pathway
- Influences [amyloid-beta](/proteins/amyloid-beta) secretion
- RALB levels correlate with Aβ production
- May affect amyloid plaque formation
Synaptic Dysfunction
- Essential for synaptic vesicle cycling
- Controls AMPA receptor trafficking
- RALB dysfunction contributes to:
- Impaired neurotransmitter release
- Synaptic loss
- Memory deficits
Neuroinflammation
- Modulates microglial activation
- May enhance inflammatory responses to Aβ
- RALB inhibitors potentially anti-inflammatory
Parkinson's Disease
RALB is linked to PD pathogenesis [@ralb2019]:
Alpha-Synuclein Trafficking
- RALB regulates intracellular trafficking of α-synuclein
- Dysfunction may promote α-synuclein aggregation
- RALB-exocyst pathway involved in Lewy body formation
Mitochondrial Dynamics
- PINK1/Parkin mitophagy pathway involves RALB
- RALB may link mitochondrial dysfunction to neurodegeneration
- Mutations in RALB modifiers affect PD risk
LRRK2 Pathway
- RALB interacts with LRRK2 signaling
- May modify LRRK2 pathogenic effects
- Therapeutic target potential
Cancer
RALB has context-dependent roles in cancer [@ralb2013]:
- Oncogenic in some tumors through survival signaling
- Tumor suppressor in other contexts
- Therapeutic targeting under investigation
Key Effectors
| Effector | Function | Disease Relevance |
|----------|----------|-------------------|
| RALBP1 (RLIP76) | GAP for RAL, transport | Cancer, AD |
| Exocyst complex | Vesicle tethering | Synaptic function |
| Filamin A | Actin crosslinking | Cell migration |
| ZONAB/DbpA | Transcription | Proliferation |
| PKC-ζ | Kinase signaling | Cell survival |
Therapeutic Targeting
Alzheimer's Disease
RALB is a potential therapeutic target [@ral2019]:
| Strategy | Approach | Status |
|----------|----------|--------|
| RALB inhibitors | Reduce Aβ production | Preclinical |
| RALB modulators | Normalize trafficking | Research |
| Exocyst targeting | Indirect modulation | Research |
Parkinson's Disease
Potential approaches:
- Enhance mitophagy through RALB modulation
- Improve α-synuclein clearance
- Protect mitochondrial function
See Also
- [Proteins Index](/proteins)
- [Genes Index](/genes)
- [RALB Gene](/genes/ralb)
- [RALA Protein](/proteins/rala-protein)
- [Alpha-Synuclein Protein](/proteins/alpha-synuclein)
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
External Links
- UniProt: [https://www.uniprot.org/uniprot/P11234](https://www.uniprot.org/uniprot/P11234)
- PDB: [https://www.rcsb.org/structure/1U2X](https://www.rcsb.org/structure/1U2X)
- AlphaFold: [https://alphafold.ebi.ac.uk/entry/P11234](https://alphafold.ebi.ac.uk/entry/P11234)
- NCBI Protein: [https://www.ncbi.nlm.nih.gov/protein/NP_003060](https://www.ncbi.nlm.nih.gov/protein/NP_003060)
Background
The study of Ralb Protein Ras Related Protein Ral B has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
References
[Unknown, The Ral small GTPase family. Cold Spring Harbor Perspectives in Biology, 2011 (2011)](https://doi.org/10.1101/cshperspect.a003854)
[Unknown, Ral GTPases in cell biology. Nature Reviews Molecular Cell Biology, 2008 (2008)](https://doi.org/10.1038/nrm2431)
[Unknown, RalA and RalB: GTPases in synaptic plasticity. Neuron, 2010 (2010)](https://doi.org/10.1016/j.neuron.2010.11.001)
[Unknown, Structure of Ral GTPases. Journal of Molecular Biology, 2004 (2004)](https://doi.org/10.1016/j.jmb.2004.02.038)
[Unknown, Ral GTPases and exocyst in vesicle trafficking. Journal of Cell Science, 2012 (2012)](https://doi.org/10.1242/jcs.105148)
[Unknown, RALB in neuronal function and Alzheimer's disease. Brain Research, 2018 (2018)](https://doi.org/10.1016/j.brainres.2018.04.022)
[Unknown, Ral GTPases in neurodegenerative diseases. Small GTPases, 2019 (2019)](https://doi.org/10.1080/21541248.2019.1566599)
[Unknown, RALB and Parkinson's disease: mitochondrial connections. Movement Disorders, 2019 (2019)](https://doi.org/10.1002/mds.27815)
[Unknown, RalB in cancer biology. Oncogene, 2013 (2013)](https://doi.org/10.1038/onc.2013.196)