Endoplasmic reticulum co-chaperone crucial for survival and virulence factor production at elevated temperatures representative of febrile patients during infection (PubMed:34566931). Contributes to virulence in a mouse model of cryptococcosis (PubMed:34566931). With chaperone CNE1, coordinately maintains ER homeostasis and contributes to maintenance of cell wall architecture (PubMed:34566931). Protein amounts are increased by ER stress elicited by tunicamycin. The TPR repeats mediate interaction with unfolded polypeptides and the J-domain is essential to stimulate the ATPase activity of the chaperone and to increase its substrate affinity during the folding cycle. Leads to hypersensitivity to endoplasmic reticulum (ER) stress caused by the N-glycosylation inhibitor tunicamycin (PubMed:34566931). Markedly impairs the elaboration of virulence factors such as the polysaccharide capsule and extracellular urease activity, when induced at 37 degrees Celsius corresponsing to the human body temperature (PubMed:34566931). Impairs also induction of the cytokines IL-6, IL-10, and MCP-1 in the lungs of mice and attenuates virulence in an intranasal murine model of cryptococcosis (PubMed:34566931). Leads to abnormal cell morphology of enlarged cells with collapsed cell walls and increased chitin within the cell walls, as well as strong growth defects at both 30 and 37 degrees Celsius when both DNJ1 and CNE1 are deleted (PubMed:34566931).