| Ribosomal Protein L23a | |
|---|---|
| Protein Name | Ribosomal Protein L23a |
| Gene Symbol | [RPL23A](/genes/rpl23a) |
| UniProt ID | [P62750](https://www.uniprot.org/uniprot/P62750) |
| Molecular Weight | 17.8 kDa |
| Subcellular Localization | Cytoplasm (ribosome), Nucleus (extraribosomal) |
| Protein Family | Ribosomal Protein L23 Family |
| Organism | Homo sapiens |
RPL23A is a highly conserved ribosomal protein that forms part of the 60S large ribosomal subunit in eukaryotes[1]. Beyond its canonical role in protein synthesis, RPL23A serves critical extraribosomal functions as a regulator of the p53 tumor suppressor pathway and as a sensor of ribosomal stress[2]. Disruptions in RPL23A function have been linked to ribosomopathies such as Diamond-Blackfan anemia, and ribosomal stress is increasingly recognized as a contributor to neuronal death in Alzheimer's Disease and Parkinson's Disease[3].
The RPL23A gene is located on chromosome 17q21 and encodes a 156-amino acid protein. The gene is ubiquitously expressed, with particularly high levels in tissues undergoing active protein synthesis including bone marrow, liver, and brain. RPL23A contains a conserved zinc-finger-like domain that mediates both rRNA binding and extraribosomal protein interactions.
RPL23A adopts a characteristic ribosomal protein fold[3:1]:
The protein sits at the surface of the 60S ribosomal subunit, positioned near the polypeptide exit tunnel where it can interact with nascent polypeptides and recruited factors.
RPL23A can undergo acetylation and phosphorylation, though the functional significance of these modifications in neurons remains incompletely characterized. Ribosomal proteins are increasingly recognized as targets of post-translational regulation in stress responses.
As a component of the 60S ribosomal subunit, RPL23A participates in:
A major extraribosomal function of RPL23A is its interaction with MDM2 (Mouse Double Minute 2)[2:1]:
This pathway connects ribosome status to p53-dependent stress responses, providing a cellular surveillance mechanism for ribosomal integrity.
RPL23A levels and localization are modulated during the integrated stress response (ISR):
In Alzheimer's Disease, several mechanisms link RPL23A to disease pathogenesis:
Ribosomal Dysfunction in AD: Post-mortem AD brain tissue shows decreased global translation and ribosomal integrity. RPL23A levels and modification status may be altered in affected neurons, contributing to proteostasis collapse.
p53 and Neuronal Apoptosis: Enhanced p53 activity in AD neurons promotes apoptosis. RPL23A-mediated p53 stabilization could contribute to the elevated neuronal death observed in AD. However, the net effect is complex — p53 activation may also eliminate severely damaged neurons.
Ribosome Quality Control: RPL23A may participate in ribosome-associated quality control (RQC) pathways that monitor translational fidelity. Impaired RQC in AD contributes to proteostasis failure.
Dopaminergic Neuron Vulnerability: Dopaminergic neurons of the substantia nigra pars compacta show particular sensitivity to ribosomal stress. RPL23A dysregulation could contribute to their selective vulnerability.
Mitochondrial Stress and Translation: PD-linked mitochondrial toxins (e.g., rotenone, MPTP) impair translation. RPL23A may act as a sensor linking mitochondrial dysfunction to p53-mediated apoptosis in affected neurons.
LRRK2 and Translation Regulation: LRRK2 mutations (common in familial PD) affect translation homeostasis. RPL23A function may intersect with LRRK2-regulated pathways.
Rare ribosomopathies affecting ribosomal proteins share features with neurodegenerative processes[1:1]:
Direct targeting of RPL23A for neurodegeneration therapy remains speculative. However, understanding RPL23A pathways informs several therapeutic approaches:
| Protein | Interaction Type | Functional Significance |
|---|---|---|
| MDM2 | Physical binding | Inhibits MDM2 E3 ligase activity, stabilizing p53 |
| 28S rRNA | Structural component | Core ribosomal function |
| p53 | Indirect via MDM2 | Stress-responsive cell fate determination |
| eIF2alpha | Functional | Participates in integrated stress response |
De Keersmaecker K, et al. Ribosomal mutations in cancer and ribosomopathies. Nature Reviews Cancer. 2015. ↩︎ ↩︎
Zhang Y, et al. Ribosomal protein L23 negatively regulates p53 activity. Molecular and Cellular Biology. 2003. ↩︎ ↩︎
Bulankina AV, et al. RPL23a and its role in ribosome biogenesis and beyond. International Journal of Molecular Sciences. 2017. ↩︎ ↩︎