Stresses such as heat shock trigger the formation of protein aggregates and the induction of a disaggregation
system composed of molecular chaperones. Recent work reveals that several cases of apparent heat-
induced aggregation, long thought to be the result of toxic misfolding, instead reflect evolved, adaptive biomolecular condensation, with chaperone activity contributing to condensate regulation. Here we show that
the yeast disaggregation system directly disperses heat-induced biomolecular condensates of endogenous
poly(A)-binding protein (Pab1) orders of magnitude more rapidly than aggregates of the most commonly used
misfolded model substrate, firefly luciferase. Beyond its efficiency, heat-induced condensate dispersal differs from heat-induced aggregate dispersal in its molecular requirements and mechanistic behavior. Our
work establishes a bona fide endogenous heat-induced substrate for long-studied heat shock proteins, isolates a specific example of chaperone regulation of condensates, and underscores needed expansion of the
proteotoxic interpretation of the heat shock response to encompass adaptive, chaperone-mediated regulation.