DnaJ (Hsp40) belongs to the DnaJ-class of molecular chaperones with a C-terminal Zn finger domain. HSP40 (DnaJ) together with DnaK and GrpE form a molecular chaperone that is involved in formation of protein complexes, protein folding, prevention of protein aggregation, and protein turnover and export. Several human neurodegenerative diseases involve the expansion of a polyglutamine within the disease proteins. Molecular chaperones such as HSP40 complexes can modulate polyglutamine pathogenesis In transgenic Drosophila disease models of Machado-Joseph disease and Huntington disease Hdj1, the Drosophila homolog to human HSP40, demonstrates substrate specificity for polyglutamine proteins suppression in combination with other molecular chapterones of neurotoxicity, and altered solubility of mutant polyglutamine proteins.
