A protein bridge to death between the ER and mitochondria

Commitment to apoptotic cell death occurs at the mito-chondria and is regulated by BCL-2 family proteins localized to this organelle. However, BIK, a resident protein of the endo-plasmic reticulum, inhibits mitochondrial BCL-2 proteins to promote apoptosis. In a recent paper in the JBC, Osterlund et al. investigated this conundrum. Surprisingly, they discov-ered that these endoplasmic reticulum and mitochondrial proteins moved toward each other and met at the contact site between the two organelles, thereby forming a 'bridge to death'.