Homo- and hetero-oligomerization of the c-Abl kinase and Abelson-interactor-1.

Oligomerization of the nonreceptor tyrosine kinase c-Abl can activate its transforming potential. Domains mediating oligomerization within the BCR-ABL and TEL-ABL oncoproteins are required for transforming activity, and fusion of inducible dimerization domains to c-Abl can generate chimeric proteins with dimerization-dependent transforming activity. We have found that c-Abl oligomerizes at high levels of expression in COS cells. This interaction is dependent on kinase activity and an intact NH(2)-terminal region of c-Abl. A binding partner of c-Abl, Abl-interactor-1 (Abi-1), similarly oligomerizes in COS cells. An oligomeric form of Abi-1 interacts with Abl both in vitro and in mammalian cells. These results suggest the possibility that oligomerization of Abl kinases, perhaps involving regulation by their interaction partners, may play a role in modulation of kinase activity in both normal and oncogenic processes.