The Bcr-Abl oncoprotein oligomerisation domain consists of a short N-terminal helix (alpha-1), a flexible loop and a long C-terminal helix (alpha-2). Together these form an N-shaped structure, with the loop allowing the two helices to assume a parallel orientation. The monomeric domains associate into a dimer through the formation of an antiparallel coiled coil between the alpha-2 helices and domain swapping of two alpha-1 helices, where one alpha-1 helix swings back and packs against the alpha-2 helix from the second monomer. Two dimers then associate into a tetramer. The oligomerisation domain is essential for the oncogenicity of the Bcr-Abl protein [1].

1: Structure of the Bcr-Abl oncoprotein oligomerization domain. Zhao X, Ghaffari S, Lodish H, Malashkevich VN, Kim PS; Nat Struct Biol. 2002;9:117-120. PMID:11780146