Involved in protein translation, propagation of [PSI+] prions, and polyamine tolerance. Functions as a nucleotide exchange factor (NEF), which accelerates the release of ADP, for the cytosolic Hsp70 chaperone SSA1 and the ribosome-associated Hsp70 chaperone SSB1. Required for fully efficient Hsp70-mediated folding of proteins. Interacts with the Hsp70 chaperones SSA1 and SSB1. Present with 13100 molecules/cell in log phase SD medium. Belongs to the FES1 family.