Enables Hsp90 protein binding activity. Involved in cellular response to glucose stimulus; cellular response to hydrogen peroxide; and cellular response to manganese ion. Predicted to be located in endoplasmic reticulum membrane; mitochondrion; and nuclear inner membrane. Predicted to be integral component of endoplasmic reticulum membrane. Predicted to be part of AIP1-IRE1 complex; IRE1-RACK1-PP2A complex; and IRE1-TRAF2-ASK1 complex. Human ortholog(s) of this gene implicated in hepatocellular carcinoma. Orthologous to human ERN1 (endoplasmic reticulum to nucleus signaling 1). [provided by Alliance of Genome Resources, Apr 2022]