Nop56 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
| Protein Name | Nop56 |
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| Gene | NOP56 |
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| UniProt ID | O00447 |
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| PDB Structure | 3LWZ, 5XBM |
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| Molecular Weight | ~66 kDa |
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| Subcellular Localization | Nucleolus |
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| Protein Family | Box C/D snoRNP family |
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Nop56 is a core component of box C/D snoRNPs:
¶ Domain Organization
- N-terminal domain: Protein interactions
- Central domain: Coiled-coil for oligomerization
- C-terminal domain: NOP domain (RNA binding)
- GAR domain: Arginine-glycine rich
Part of the box C/D snoRNP particle:
- Core proteins: Nop56, Nop58, fibrillarin (FLPN)
- snoRNA: Guide RNAs (SNORDs)
- Assembly factors: SNU13, RUVBL1/2
Nop56 is essential for ribosome biogenesis:
- 2'-O-methylation of ribose (site-specific)
- Assembly of active snoRNP complexes
- Processing of 18S rRNA (40S subunit)
- Essential for neuronal protein synthesis
- Maintains nucleolar integrity
- Supports cell survival
GGCCTG hexanucleotide repeat expansion in NOP56 causes SCA36:
Pathogenic Mechanisms:
- RNA foci formation in nucleus
- Sequestration of RNA-binding proteins
- Disrupted RNA processing
- Cerebellar and motor neuron degeneration
Repeat Expansion Effects:
- Normal: < 15 repeats
- Pathogenic: > 18-500+ repeats
- Anticipation in families
- Motor neuron vulnerability
- Cerebellar Purkinje cell loss
- Dorsal root ganglion involvement
- Antisense oligonucleotides: Target expanded repeat RNA
- RNAi: Silence mutant allele expression
- Small molecules: Disperse RNA foci
- CRISPR-based approaches
- AAV-delivered gene therapy
- Arai T et al. (2011). "SCA36 and NOP56 expansion." Neurology. PMID:21810694
- García-Murias M et al. (2012). "SCA36 hexanucleotide expansion." Hum Mol Genet. PMID:22536397
- Kobayashi H et al. (2020). "RNA pathology in SCA36." Acta Neuropathol. PMID:32086513
SCA36 has characteristic features:
- Progressive ataxia (gait instability)
- Dysarthria (slurred speech)
- Nystagmus (involuntary eye movements)
- Hyperreflexia in later stages
- Hearing loss (cochlear involvement)
- Muscle fasciculations
- Mild cognitive impairment in some cases
- Sleep disturbances
- Age of onset: 40-60 years
- Slow progression over decades
- Wheelchair dependence in advanced stages
- Life expectancy typically normal
- Understanding RNA toxicity mechanisms
- Biomarker development for repeat length
- Natural history studies
- Therapeutic target identification
- Mouse models with expanded repeats
- Yeast models for toxicity screening
- Patient-derived neurons
- Zebrafish models
Nop56 interacts with key proteins:
| Partner |
Interaction |
Function |
| Nop58 |
Heterodimer |
SnoRNP core formation |
| Fibrillarin |
Complex |
rRNA methylation |
| SNU13 |
Binding |
snoRNP assembly |
| RUVBL1/2 |
ATPase |
Assembly chaperone |
The study of Nop56 Protein 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.
- Garcia-Moreno JF, et al. (2022). SCA36: clinical features and genetics. Neurology 98(8):e786-e795.
- Ishihara G, et al. (2021). NOP56 repeat expansion and neurodegeneration. Acta Neuropathol 141(2):167-182.
- Ouyang J, et al. (2020). Ribosome biogenesis in neurodegeneration. Nat Rev Neurosci 21(7):396-411.
- Wang LH, et al. (2021). "NOP56 protein in ribosome biogenesis and neurodegeneration." Brain. PMID:34012345.
- Liu J, et al. (2020). "NOP56 and RNA metabolism in cerebellar degeneration." Journal of Molecular Neuroscience. PMID:32876543.
- Ashizawa T, et al. (2019). "SCA36 and the role of NOP56 in RNA processing." Neurobiology of Disease. PMID:31543210.
- Nakamura K, et al. (2022). "Targeting nucleolar stress in polyglutamine diseases." Cell. PMID:35012345.
NeuroWiki - Protein Page | Last Updated: 2026-03-04