DnaJ homolog subfamily A member 1

DNAJA1 (DnaJ homolog subfamily A member 1) is a molecular co-chaperone that works with HSPA8/Hsc70 and HSPA1B to regulate protein folding, transport, and stress responses (UniProt: P31689). It stimulates ATP hydrolysis by heat shock protein A1A and plays a critical role in translocating proteins across the mitochondrial membrane. Additionally, DNAJA1 negatively regulates BAX translocation to mitochondria during cellular stress, protecting cells from apoptosis, though it can also promote apoptosis under specific conditions such as anisomycin or UV exposure (UniProt: P31689).

In the context of Alzheimer's Disease, DNAJA1 expression is significantly downregulated in post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics). The protein showed a mean log2 fold-change of −0.39 across the measured subcellular fractions in TMT-labeled quantitative proteomics analysis. This downregulation suggests compromised protein quality control and mitochondrial homeostasis mechanisms in AD pathology, potentially contributing to the accumulation of misfolded proteins characteristic of neurodegeneration.