BID is a member of the BCL-2 superfamily of proteins are key regulators of programmed cell death, hence this family is related to Pfam:PF00452 . BID is a pro-apoptotic member of the Bcl-2 superfamily and as such posses the ability to target intracellular membranes and contains the BH3 death domain. The activity of BID is regulated by a Caspase 8-mediated cleavage event, exposing the BH3 domain and significantly changing the surface charge and hydrophobicity, which causes a change of cellular localisation [1].

1: Solution structure of the proapoptotic molecule BID: a structural basis for apoptotic agonists and antagonists. McDonnell JM, Fushman D, Milliman CL, Korsmeyer SJ, Cowburn D; Cell 1999;96:625-634. PMID:10089878