Ribosome-associated J protein-Hsp70 chaperones promote nascent-polypeptide folding and normal translational fidelity. This entry includes J protein DnaJC2 from humans, Zuo1 from budding yeasts, and their homologues from other animals, fungi and plants []. DnaJC2 stimulates the ATPase activity of Hsp70 (Ssb1/2 in yeast) []. Zuo1 forms a stable heterodimeric complex termed ribosome-associated complex (RAC) with Ssz1 (an atypical Hsp70 family member, known as HspA14 in humans), this complex is then anchored to the ribosome via its Zuo1 subunit []. These three proteins (Ssb, Zuo1 and Ssz1) referred to as a chaperone triad lay a role together in folding of nascent polypeptides []. Moreover, Zuo1 has been shown to interact with the 40S and 60S ribosomal subunits in budding yeasts [].
