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Cyclic AMP-dependent kinase regulates Raf-1 kinase mainly by phosphorylation of serine 259

Version 2 2024-06-04, 14:52
Version 1 2021-09-23, 08:25
journal contribution
posted on 2024-06-04, 14:52 authored by Amardeep DhillonAmardeep Dhillon, C Pollock, H Steen, PE Shaw, H Mischak, W Kolch
ABSTRACT The Raf-1 kinase activates the ERK (extracellular-signal-regulated kinase) pathway. The cyclic AMP (cAMP)-dependent protein kinase (PKA) can inhibit Raf-1 by direct phosphorylation. We have mapped all cAMP-induced phosphorylation sites in Raf-1, showing that serines 43, 259, and 621 are phosphorylated by PKA in vitro and induced by cAMP in vivo. Serine 43 phosphorylation decreased the binding to Ras in serum-starved but not in mitogen-stimulated cells. However, the kinase activity of a RafS43A mutant was fully inhibited by PKA. Mutation of serine 259 increased the basal Raf-1 activity and rendered it largely resistant to inhibition by PKA. cAMP increased Raf-1 serine 259 phosphorylation in a PKA-dependent manner with kinetics that correlated with ERK deactivation. PKA also decreased Raf-1 serine 338 phosphorylation of Raf-1, previously shown to be required for Raf-1 activation. Serine 338 phosphorylation of a RafS259A mutant was unaffected by PKA. Using RafS259 mutants we also demonstrate that Raf-1 is the sole target for PKA inhibition of ERK and ERK-induced gene expression, and that Raf-1 inhibition is mediated mainly through serine 259 phosphorylation.

History

Journal

Molecular and Cellular Biology

Volume

22

Pagination

3237-3246

Location

United States

ISSN

0270-7306

eISSN

1098-5549

Language

English

Publication classification

C1.1 Refereed article in a scholarly journal

Issue

10

Publisher

AMER SOC MICROBIOLOGY

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