| Description: | Human HSP40/DnaJ proteins comprise a large protein family, members of which feature the J domain (named after the bacterial DnaJ protein) (1). The J-domain spans the first 75 N-terminal amino acids and is separated from the C-terminal by a glycine/phenylalanine-rich domain (2). There are two main types of HSP40; type 1 DNAJ proteins including HDJ2 and yeast YdjI; type II includes yeast Sis1 and human Hdj1. Whereas type I possesses a zinc finger domain which helps in the function of protein folding. (3, 4), type II does not.Members of the HSP40/DnaJ family play diverse roles in many cellular processes, such as folding, translocation, degradation and assembly of multi-protein complexes. HSP40 stimulates the ATPase activity of HSP70 which in turn causes conformational changes of the unfolded proteins (5, 6). The HSP40-HSP70-unfolded protein complex further binds to co-chaperones Hip, Hop and HSP90 which leads to protein folding, or components of protein degradation machinery CHIP and BAG-1 (7). |
