This is a family of pro-apoptotic Bcl-x proteins, B cell leukaemia/lymphoma 2, or BIKs. BIK proteins rely for their activity upon an intact BH3 domain lying between residues 48 and 80, as in UniProt:Q13323.

1: Bcl-2-family proteins: the role of the BH3 domain in apoptosis. Kelekar A, Thompson CB; Trends Cell Biol. 1998;8:324-330. PMID:9704409

2: Role of the BH3 (Bcl-2 homology 3) domain in the regulation of apoptosis and Bcl-2-related proteins. Lutz RJ; Biochem Soc Trans. 2000;28:51-56. PMID:10816098

3: Bik, a novel death-inducing protein shares a distinct sequence motif with Bcl-2 family proteins and interacts with viral and cellular survival-promoting proteins. Boyd JM, Gallo GJ, Elangovan B, Houghton AB, Malstrom S, Avery BJ, Ebb RG, Subramanian T, Chittenden T, Lutz RJ, et al.; Oncogene. 1995;11:1921-1928. PMID:7478623

4: Induction of apoptosis by human Nbk/Bik, a BH3-containing protein that interacts with E1B 19K. Han J, Sabbatini P, White E; Mol Cell Biol. 1996;16:5857-5864. PMID:8816500