BRI3 Binding Protein (BRI3BP)

BRI3BP contains an open reading frame encoding 251 amino acids. The calculated molecular weight of the deduced protein is 27.8 kU. The predicted isoelectric point is 9.48. Northern hybridization showed its mRNA was highly expressed in brain, kidney, and liver. BRI3BP overexpression enhanced both mitochondrial cytochrome c release and caspase-3 activity in etoposide-treated cells. In response to etoposide, the ER reorganized into irregularly shaped lamellae in mock-transfected cells, whereas in BRI3BP-overexpressing cells, such reorganization was not observed. These observations suggest that BRI3BP is involved in the structural dynamics of the ER and affects mitochondrial viability. Taken together, BRI3BP, widely expressed in animal cell types, seems to possess a pro-apoptotic property and can potentiate drug-induced apoptosis.