HSP40

HSP40 (also known as DnaJ proteins) functions as a molecular co-chaperone that regulates HSP70 activity and assists protein folding^[1][2][3]. Mechanistically, HSP40 recognizes unfolded or misfolded client proteins and delivers them to HSP70, stimulating ATP hydrolysis and promoting proper substrate folding^[1][2]. HSP40 participates in key cellular processes including protein quality control, endoplasmic reticulum-associated degradation (ERAD), and stress-induced proteostasis, which are essential for maintaining neuronal and cardiac cell integrity^[2][3]. In disease models, HSP40 dysfunction contributes to neurodegenerative disorders such as Parkinson’s disease and protein-misfolding myopathies, including LGMDD1, through disrupted client recognition and HSP70 cooperation^[3][4]. Compared with related isoforms, specific HSP40 members like DNAJB6 exhibit unique substrate specificity and domain-dependent regulatory mechanisms that influence client degradation or stabilization^[4][2]. Experimental studies demonstrate that HSP40 modulates the stability and trafficking of ion channels, including hERG and KCNQ4, indicating its utility in therapeutic protein rescue strategies^[2]. Small-molecule modulators and genetic manipulations targeting HSP40 interactions provide insights into co-chaperone regulation and offer potential intervention points for proteostasis-related pathologies^[1][5]. Therefore, HSP40 acts as a versatile node within chaperone networks, integrating stress signals, client specificity, and co-chaperone dynamics for cellular homeostasis and experimental applications.