Enables endoribonuclease inhibitor activity and enzyme binding activity. Involved in cellular response to unfolded protein; negative regulation of RNA metabolic process; and negative regulation of immunoglobulin production. Acts upstream of or within endoplasmic reticulum calcium ion homeostasis; intrinsic apoptotic signaling pathway in response to endoplasmic reticulum stress; and negative regulation of endoplasmic reticulum stress-induced intrinsic apoptotic signaling pathway. Predicted to be located in endoplasmic reticulum membrane and mitochondrial membrane. Is expressed in head and retina. Orthologous to human TMBIM6 (transmembrane BAX inhibitor motif containing 6). [provided by Alliance of Genome Resources, Apr 2022]