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Involvement of B‐Raf in Ras‐induced Raf‐1 activation
Author(s) -
Mizutani Shin,
Inouye Kaoru,
Koide Hiroshi,
Kaziro Yoshito
Publication year - 2001
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(01)02992-1
Subject(s) - activator (genetics) , kinase , protein kinase a , transfection , chemistry , extracellular , microbiology and biotechnology , c raf , signal transduction , mapk/erk pathway , mitogen activated protein kinase kinase , biology , biochemistry , receptor , gene
The mechanism of Ras‐induced Raf‐1 activation is not fully understood. Previously, we identified a 400‐kDa protein complex as a Ras‐dependent Raf‐1 activator. In this study, we identified B‐Raf as a component of this complex. B‐Raf was concentrated during the purification of the activator. Immunodepletion of B‐Raf abolished the effect of the activator on Raf‐1. Furthermore, B‐Raf and Ras‐activated Raf‐1 co‐operatively, when co‐transfected into human embryonic kidney 293 cells. On the other hand, Ras‐dependent extracellular signal‐regulated kinase/mitogen‐activated protein kinase kinase stimulator (a complex of B‐Raf and 14‐3‐3) failed to activate Raf‐1 in our cell‐free system. These results suggest that B‐Raf is an essential component of the Ras‐dependent Raf‐1 activator.