Pathway · 2 proteins

Early folding support

DnaK/DnaJ and trigger-factor annotations identify folding-support functions.

How it works

Nascent or non-native polypeptides expose binding surfaces that can recruit trigger factor or DnaK-associated chaperones. These systems assist folding without specifying the final structure from a new template.
In the DnaK cycle, DnaJ promotes substrate-associated ATP hydrolysis and GrpE promotes nucleotide exchange. Trigger factor provides a distinct early folding-support route associated with protein synthesis.
Repeated binding and release can limit aggregation and permit folding. The presence of these chaperones does not mean every client uses the same sequence of interactions or necessarily reaches a native state.

Grouped by the atlas’s curated pathway map. The table order is not a proven reaction order.

Protein	EC	Reaction (UniProt)	Metal or cluster	Amino acids	Certainty
Trigger factor	5.2.1.8	[protein]-peptidylproline (omega=180) = [protein]-peptidylproline (omega=0)	—	478	Step named
Protein GrpE	—	—	—	182	Step named

These proteins are described under another pathway, but also take part here.

Protein	EC	Reaction (UniProt)	Metal or cluster	Amino acids	Certainty
Chaperone protein DnaKHome: Folding and stabilization	—	—	—	632	Step named

How are new protein chains protected as they leave the ribosome?

Naturalistic proposal

None of the books searched discusses the origin of chaperones that act on new chains.

Design analysis

Trigger factor sits at the ribosome exit and shields the growing chain until it can fold, which links protein synthesis directly to folding.

The wider question for this part of the cell: origins for building proteins and folding them.

Atlas pathway grouping from the VF5 reference-genome system map (Deckert et al. 1998; Braakman & Smith 2014)