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Discrete cytosolic macromolecular BRAF complexes exhibit distinct activities and composition
Author(s) -
Diedrich Britta,
Rigbolt Kristoffer TG,
Röring Michael,
Herr Ricarda,
KaeserPebernard Stephanie,
Gretzmeier Christine,
Murphy Robert F,
Brummer Tilman,
Dengjel Jörn
Publication year - 2017
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.201694732
Subject(s) - biology , cytosol , composition (language) , biochemistry , microbiology and biotechnology , enzyme , philosophy , linguistics
As a central element within the RAS / ERK pathway, the serine/threonine kinase BRAF plays a key role in development and homeostasis and represents the most frequently mutated kinase in tumors. Consequently, it has emerged as an important therapeutic target in various malignancies. Nevertheless, the BRAF activation cycle still raises many mechanistic questions as illustrated by the paradoxical action and side effects of RAF inhibitors. By applying SEC ‐ PCP ‐ SILAC , we analyzed protein–protein interactions of hyperactive BRAF V 600E and wild‐type BRAF ( BRAF WT ). We identified two macromolecular, cytosolic BRAF complexes of distinct molecular composition and phosphorylation status. Hyperactive BRAF V 600E resides in large complexes of higher molecular mass and activity, while BRAF WT is confined to smaller, slightly less active complexes. However, expression of oncogenic K‐Ras G12V , either by itself or in combination with RAF dimer promoting inhibitors, induces the incorporation of BRAF WT into large, active complexes, whereas pharmacological inhibition of BRAF V 600E has the opposite effect. Thus, the quaternary structure of BRAF complexes is shaped by its activation status, the conformation of its kinase domain, and clinically relevant inhibitors.