Toll-like receptor (TLR)-specific co-chaperone for HSP90B1. Required for proper TLR folding, except that of TLR3, and hence controls TLR exit from the endoplasmic reticulum. Consequently, required for both innate and adaptive immune responses. Interacts with HSP90B1; this interaction is disrupted in the presence of ATP. Interacts with TLR1, TLR2, TLR4 and TLR9. Strongest interaction with TLR4. The birth rate of knockout mice on a C57BL/6 background is very low (approximately 10% of pups). The animals appear normal, but their growth after birth is severely retarded. Half of them die by the end of the weaning period. Mutant mice have profoundly impaired T-helper type 1 lymphocyte (Th1)-mediated responses (PubMed:17998391). On a BALB/c background, under resting conditions, they show spastic or dystonic features and, during the open field test, they exhibit hyperactivity and anxiety. Their resting electroencephalography show enhanced activity in the fast beta frequency band (20-35 Hz). They do not show any apparent structural brain anomaly (PubMed:29394991). Belongs to the canopy family.