Chaperone that suppresses aggregation of proteins with long polyglutamine (polyQ) tracts (PubMed:30029002). Acts by promoting degradation of polyQ aggregates by the proteasome (PubMed:30029002). Ubiquitinated (Probable). Degraded by the proteasome; degradation is stimulated by polyglutamine (polyQ) aggregates (PubMed:30029002). Expansion of polyglutamine (polyQ) tracts, resulting in protein aggregation, is a cause of neurodegenerative diseases in human (PubMed:30029002). D.discoideum, which encodes many proteins with long polyQ tracts, is resistant to polyQ aggregation, thanks to proteins like hssl63/srcp1 (PubMed:30029002). Belongs to the hssA/B family.