Plays an indispensable role in the organization of KRT8/KRT18 filaments. Acts as an endogenous molecular chaperone for neuronal proteins including huntingtin. Suppresses aggregation and toxicity of polyglutamine-containing, aggregation-prone proteins (By similarity). Has a stimulatory effect on the ATPase activity of HSP70 in a dose-dependent and time-dependent manner and hence acts as a co-chaperone of HSP70. Also reduces cellular toxicity and caspase-3 activity (By similarity). Homooligomer (By similarity). Interacts with BAG3, HSPB8 and STUB1 (By similarity). Interacts with HSP70, KRT18 and PTTG. Isoform B interacts with histone deacetylases HDAC4, HDAC6, and SIRT2, HDAC activity is required for antiaggregation (By similarity). Interacts with ALKBH1. The antiaggregation activity of resides in the serine-rich region and the C-terminus.