Component of the ribosome-associated complex (RAC), a heterodimeric chaperone complex involved in regulation of accurate translation termination and in folding or maintaining nascent polypeptides in a folding-competent state. RAC stimulates the ATPase activity of the ribosome-associated pool of Hsp70-type chaperones SSB1/SSB2 that bind to the nascent polypeptide chain (By similarity). RAC is a heterodimer of the Hsp70/DnaK-type chaperone ssz1 and the Hsp40/DnaJ-type chaperone zuo1. RAC associates with ribosomes via zuo1 (By similarity).