特異性：Human Bid Members of the Bcl-2 family are pro- or antiapoptotic proteins that process one or several of the Bcl-2 homology (BH) domains. Bid is a proapoptotic, BH3-domain-only member or BH3-only protein (BOP) of the Bcl-2 family. Bid is localized in the cytosolic fraction of living cells as an inactive precursor. Activation of Bid occurs upon its cleavage by caspase-8 in the Fas and TNF- alpha apoptotic signaling pathways. Recent studies have suggested that Bid is also cleaved and activated by granzyme B, calpain and lysosomal extracts. Cleaved Bid translocates to mitochondria where it induces the release of cytochrome c from the intermembrane space of the mitochondria. The release of cytochrome c initiates apoptosis by activating downstream caspases through binding to Apaf-1. Bid has also been shown to interact with with Bax, another Bcl-2 family protein, to trigger a conformational change in Bax leading to the dimerization and integration of Bax into the outer mitochondrial membrane and activating the release of cytochrome c.1-10
