Publications

Abstract

Signal transduction by Raf-kinases involves their dimerization, a process that underlies the paradoxical effects of Raf-inhibitors and that is also considered for novel therapeutic approaches. A central cluster within the dimer interface (DIF) of the kinase domain and 14-3-3 proteins are implicated in Raf-dimerization. However, the importance of the DIF for the signaling potential of full-length B-Raf and its oncogenic counterparts is unknown. Here, we show that the DIF plays a pivotal role for the activity of B-Raf and several of its gain-of-function mutants. In striking contrast, the most clinically relevant mutant, B-RafV600E, is highly resilient to mutations in the DIF, the C-terminal 14-3-3 binding motif, or a combination of both. Based on our findings that B-RafV600E forms stable dimers, extended protomer contacts and higher-ordered complexes, we propose that the dimerization and transforming activity of B-RafV600E stems from the concerted action of the DIF, 14-3-3 proteins and its active conformation.