| RALB Protein — RAS-Related Protein Ral-B | |
|---|---|
| Gene | RALB |
| UniProt | P11234 |
| PDB Structures | 1U2X, 2KWI, 1MS9 |
| Molecular Weight | ~23 kDa |
| Length | 206 amino acids |
| Subcellular Localization | Cytoplasm, Plasma membrane, Vesicles, Synapses |
| Protein Family | RAS GTPase family, Ral subfamily |
| Aliases | Ras-related protein Ral-B, Ral-B |
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.
RALB (RAS-Related Protein Ral-B) is a small GTPase belonging to the Ras superfamily of monomeric G proteins [1]. 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 [2].
RALB is one of two Ral proteins (RALA and RALB) that share approximately 50% homology with Ras proteins but have distinct cellular functions [3]. 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.
Like other small GTPases, RALB has a characteristic fold [4]:
N-terminus
|
GxxxxGKST ---- Switch I ---- Switch II ---- GxxxxGKST
[P-loop] [GTP binding] [GTP hydrolysis]
|
C-terminus (CAAX motif: CQLN)
| 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 |
| State | Conformation | Effectors Bound |
|---|---|---|
| GTP | Active | Ral effectors (exocyst, RalBP1, etc.) |
| GDP | Inactive | No effectors |
| GDP+Pi | Transition | Intermediate |
RALB cycles between active and inactive states [2]:
GDP-RALB + GEF → GDP release → RALB-GTP + effectors
↓
GAPs
↓
GTP hydrolysis
↓
GDP-RALB + Pi
↓
GDIs
↓
Cytosolic pool
| Regulator | Function | Examples |
|---|---|---|
| GEFs | Activate (GTP binding) | RALGDS, RGL, RGL3 |
| GAPs | Inactivate (GTP hydrolysis) | RALGAPs |
| GDIs | Extract from membranes | RHOGDI |
RALB controls vesicular transport [5]:
In neurons, RALB is particularly important for [6]:
RALB is implicated in AD through multiple mechanisms [6][7]:
RALB is linked to PD pathogenesis [8]:
RALB has context-dependent roles in cancer [9]:
| 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 |
RALB is a potential therapeutic target [7]:
| Strategy | Approach | Status |
|---|---|---|
| RALB inhibitors | Reduce Aβ production | Preclinical |
| RALB modulators | Normalize trafficking | Research |
| Exocyst targeting | Indirect modulation | Research |
Potential approaches:
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.