chaperonen

Chaperonen are a proposed family of molecular chaperones involved in the folding, stabilization, and assembly of proteins within cells. The term, derived from "chaperone" with a suffix used for protein families, is used in some contemporary models to describe a distinct class that interacts with nascent or unfolded substrates, either independently or in cooperation with classical chaperone systems.

Chaperonen were identified through comparative genomics and structural motif analyses that highlighted a conserved set of small, soluble proteins co-located with known chaperone genes. The name was introduced in a 2018–2019 synthesis of emerging folding factors to distinguish them from canonical chaperonins and Hsp70-like proteins.

Typically 12–25 kDa, chaperonen form homo-oligomeric assemblies such as rings or dimers. They bind exposed hydrophobic regions on unfolding substrates to prevent aggregation and can either hold substrates for later refolding or directly channel them to downstream chaperones. ATP dependence varies among family members.

Chaperonen have been reported in bacteria, archaea, and some eukaryotes, with expression often upregulated under heat, oxidative, or proteotoxic stress. They are thought to function as modulators of proteostasis, acting alongside classical systems to cope with rapid proteome changes.

Because the concept remains evolving and terminology unsettled, ongoing research aims to clarify their evolutionary origin, exact mechanisms, and potential applications in biotechnology and medicine, including strategies to enhance recombinant protein production or to perturb proteostasis in pathogens.