Isolated by screening for Bcl-2 interacting proteins, Bad shows significant homology to Bcl-2 within the Bcl-2 homology domains 1 and 2 (BH1 and BH2). In addition, several other proteins involved in cell death such as Bax, Bcl-X[L], Mcl-1, and A1 share similar homology with Bcl-2. Bcl-2 is known to oppose several apoptotic signals and is considered to be a central downstream cell death repressor. Bcl-X[L] represses apoptosis, but its short form, Bcl-X[S], promotes cell death. Bax is known to homodimerize as well as heterodimerize with Bcl-2. An excess concentration of Bax opposes the ability of Bcl-2 to repress cell death. Bad can selectively dimerize with Bcl-X[L] and Bcl-2, but not with Bax, Bcl-X[S], Mcl-1, A1, or itself. In mammalian cells, Bad binds more strongly to Bcl-X[L] than Bcl-2. This may explain why Bad reverses the death repressor activity of Bcl-X[L], but not that of Bcl-2. The formation of the Bad-Bcl-X[L] heterodimer displaces Bax and restores favorable conditions for apoptosis.
This antibody is routinely tested by immunofluoresence microscopy. Other applications were tested at BD Biosciences Pharmingen during antibody development only or reported in the literature.