Bok (D7V2N) Rabbit mAb #86875

The Bcl-2 family consists of a number of evolutionarily conserved proteins containing Bcl-2 homology domains (BH) that regulate apoptosis through control of mitochondrial membrane permeability and release of cytochrome c (1-3). Four BH domains have been identified (BH1-4) that mediate protein interactions. The family can be separated into three groups based upon function and sequence homology: pro-survival members include Bcl-2, Bcl-xL, Mcl-1, A1 and Bcl-w; pro-apoptotic proteins include Bax, Bak and Bok; and "BH3 only" proteins Bad, Bik, Bid, Puma, Bim, Bmf, Noxa and Hrk. Interactions between death-promoting and death-suppressing Bcl-2 family members has led to a rheostat model in which the ratio of pro-apoptotic and anti-apoptotic proteins controls cell fate (4). Thus, pro-survival members exert their behavior by binding to and antagonizing death-promoting members. In general, the "BH3-only members" can bind to and antagonize the pro-survival proteins leading to increased apoptosis (5). While some redundancy of this system likely exists, tissue specificity, transcriptional and post-translational regulation of many of these family members can account for distinct physiological roles.
Like other family members Bok was identified based on sequence homology and interaction with select anti-apoptotic family members (6,7). Although Bok was originally described to be predominantly expressed in reproductive tissues such as ovary, testis and uterus (6), subsequent studies have found selective expression of Bok in a number of adult and development tissues (7). The Bok gene is frequently mutated in human tumors, suggesting a tumor suppressor activity (8). While Bok is structurally similar to the pro-apoptotic proteins Bax and Bak, it appears to be functionally distinct. Loss of Bok in mice did not have an overt effects phenotype (9). However, additional studies have shown that Bok plays a distinct role in apoptosis in response to endoplasmic reticulum stress (10,11). The stability of Bok is regulated by the endoplasmic-reticulum-associated degradation (ERAD) pathway (11). Bok expression is induced by proteasome inhibitors and triggers apoptosis by these agents (11).