DNAJC28 (DnaJ Heat Shock Protein Family Member C28), also known as C21orf91, is a molecular chaperone belonging to the DNAJ/Hsp40 family of proteins. While functionally characterized to a limited extent, this gene encodes a protein containing the conserved J-domain characteristic of DNAJ chaperones, which function as co-chaperones with Hsp70 proteins to facilitate protein folding, refolding, and clearance of misfolded proteins. The DNAJ family represents a crucial component of the cellular proteostasis network, and while DNAJC28 itself has not been directly linked to neurodegenerative diseases, the broader family has significant associations with various neurological conditions[1][2].
| Property | Value |
|---|---|
| Gene Symbol | DNAJC28 |
| Gene Name | DnaJ Heat Shock Protein Family Member C28 |
| Chromosomal Location | 21q22.11 |
| NCBI Gene ID | 254268 |
| OMIM | 619044 |
| UniProt | Q9H0Z2 |
| Ensembl ID | ENSG00000178104 |
| Aliases | C21orf91, DJC28 |
| Gene Type | Protein coding |
| Strand | Plus strand |
| Exon Count | 10 |
DNAJC28 protein contains the canonical features of DNAJ family members:
The J-domain is the most conserved feature of DNAJ proteins and is essential for interaction with Hsp70/DnaK chaperones. This domain contains a highly conserved HPD motif (His-Pro-Asp) that is critical for stimulating Hsp70 ATPase activity and facilitating substrate transfer[3][4].
| Property | Value |
|---|---|
| Protein Length | ~365 amino acids |
| Molecular Weight | ~41 kDa |
| Subcellular Location | Cytoplasm (predicted) |
| Tissue Expression | Testis-specific |
The DNAJ/Hsp40 family represents a critical component of the molecular chaperone network in eukaryotic cells. These proteins function as co-chaperones, working in concert with Hsp70 proteins to regulate protein folding, refolding, assembly, and degradation[1:1][4:1].
The general mechanism of DNAJ function involves:
While DNAJC28 remains incompletely characterized, several aspects of its biology can be inferred:
Testis-specific expression: DNAJC28 demonstrates highly restricted expression to testicular tissue, suggesting specialized functions in spermatogenesis
Spermatogenesis role: During sperm development, extensive protein remodeling occurs, requiring robust chaperone activity. DNAJC28 may assist in:
Hsp70 collaboration: Like all DNAJ proteins, DNAJC28 likely works with specific Hsp70 partners (such as HSPA2 in testis) to facilitate protein homeostasis
The DNAJ family broadly participates in:
While DNAJC28 itself has not been directly implicated in neurodegenerative diseases, several family members have established roles in neurodegeneration, providing context for understanding potential mechanisms[2:1][5].
| Gene | Disease Association | Mechanism |
|---|---|---|
| DNAJC5 | Neuronal ceroid lipofuscinosis (NCL) | Synaptic vesicle trafficking, neurotransmitter release |
| DNAJC6 | Early-onset Parkinson's disease | Endocytic recycling, synaptic function |
| DNAJC7 | Tauopathies, Alzheimer's disease | tau protein processing, protein aggregation |
| DNAJC13 | Parkinson's disease | Endosomal trafficking, lysosomal function |
| DNAJC12 | Parkinson's disease | Chaperone activity in dopaminergic neurons |
Neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis share common pathological features related to protein homeostasis failures[6][7]:
The Hsp70/Hsp40 chaperone system is central to maintaining proteostasis, and its dysfunction may contribute to disease pathogenesis. Therapeutic strategies targeting this system are actively being explored[8][9].
Modulating DNAJ/Hsp40 function represents a promising therapeutic approach:
DNAJC28 demonstrates highly restricted tissue expression:
| Tissue | Expression Level | Notes |
|---|---|---|
| Testis | Very High | Primary expression site |
| Brain | Minimal/Not detectable | Consistent with testis-specific pattern |
| Other tissues | Minimal/Not detectable | Broadly low expression |
Based on bioinformatic predictions:
Based on available literature:
Significant knowledge gaps remain:
Kampinga et al. DNAJ heat shock proteins in protein homeostasis, Cell (2019). 2019. ↩︎ ↩︎
Kalivereti et al. The DNAJ proteins in neurodegeneration, J Mol Neurosci (2020). 2020. ↩︎ ↩︎
Schiene et al. J-domain proteins as Hsp70 co-chaperones, Curr Protein Pept Sci (2004). 2004. ↩︎
Hasson et al. The diverse functions of DNAJ/Hsp40 chaperones, J Biol Chem (2015). 2015. ↩︎ ↩︎
Chuang et al. Hsp40 and neurodegeneration, Nat Rev Neurol (2015). 2015. ↩︎
Balupuri et al. Molecular chaperones in AD pathogenesis, J Alzheimer's Dis (2021). 2021. ↩︎
Ciso et al. Hsp70/Hsp40 system in PD, Mov Disord (2019). 2019. ↩︎
Lin et al. Chaperone therapy for neurodegeneration, Nat Rev Drug Discov (2018). 2018. ↩︎
Yoshida et al. DNAJ family in protein quality control, Cell Stress Chaperones (2019). 2019. ↩︎