ATPase involved in protein folding and NLS-directed nuclear transport; HSP70 family member; required for Ub-dependent degradation of short-lived proteins; Ydj1p accelerates ATP hydrolysis and release; mechanosensor-mediated phosphorylation by Pkc1p promotes the global heat shock response; localizes to the nucleus, cytoplasm and cell wall; role in [URE3] prion propagation and vacuolar-mediated degradation of gluconeogenic enzymes; targets Hsp104p to prion fibrils; 98% identity with paralog Ssa2p