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Updated: Aug 6, 2026

Characterize Disease-related Mutants of RAF Family Kinases by Using a Set of Practical and Feasible Methods
07:49

Characterize Disease-related Mutants of RAF Family Kinases by Using a Set of Practical and Feasible Methods

Published on: July 17, 2019

Mechanism of MEK1 phosphorylation by the N-terminal acidic motif-mediated asymmetric BRAF dimer

Yasushi Kondo1, Judith Notbohm2, Ignacio Navas Camacho3

  • 1PSI Center for Life Sciences, Laboratory of Biomolecular Research, Paul Scherrer Institute, Villigen PSI, Switzerland.

Molecular Cell
|July 21, 2026
PubMed

Insights

The N-terminal acidic (NtA) motif of BRAF kinase is crucial for its full catalytic activity, not just membrane recruitment. Structural and cellular data reveal how this motif drives asymmetry in BRAF activation, impacting cancer genetics.

Area of Science:

  • Molecular Biology
  • Structural Biology
  • Cancer Research

Background:

  • The RAF/MEK/ERK signaling pathway is vital for cell regulation and often dysregulated in cancers.
  • Mutations in B-type rapidly accelerated fibrosarcoma (BRAF) kinase are found in approximately 90% of RAF-mutant cancers.
  • A proposed model suggests the N-terminal acidic (NtA) motif of BRAF promotes activating asymmetric dimerization, but lacks structural evidence.

Purpose of the Study:

  • To elucidate the structural and functional role of the NtA motif in BRAF kinase activation.
  • To reconcile the genetic understanding of RAF mutations in cancer with structural biology insights.
  • To investigate the mechanism of BRAF dimerization and substrate binding.

Main Methods:

  • X-ray crystallography to determine the structures of BRAF dimers bound to MEK1.
  • Biochemical assays to assess kinase activity and protein interactions.
  • Cellular experiments to evaluate the role of the NtA motif in BRAF function.

Main Results:

  • Structures of NtA-mediated asymmetric BRAF dimers bound to the substrate MEK1 were determined.
  • The NtA motif is essential for the fully catalytically active state of BRAF, but not for KRAS-mediated plasma membrane recruitment.
  • A post-catalytic state structure, with BRAF bound to phosphorylated MEK1, provided further mechanistic insights.

Conclusions:

  • The NtA motif drives asymmetry in BRAF activation, essential for its full catalytic potential.
  • This study provides structural and cellular evidence supporting the role of the NtA motif in BRAF kinase function.
  • The findings bridge the gap between cancer genetics and structural biology regarding BRAF activation mechanisms.
Keywords:
BRAFMAPK/ERK signalingMEKmelanoma

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