The phosphorylation and dephosphorylation of proteins, catalysed by protein kinases and phosphatases, is the major mechanism for the transduction of intracellular signals in eukaryotic organisms. Signalling pathways often comprise multiple phosphorylation/dephosphorylation steps and a long-standing hypothesis to explain this phenomenon is that of the protein kinase cascade, in which a signal is amplified as it is passed from one step in a pathway to the next. This review represents a re-evaluation of this hypothesis, using the signalling network in which the SnRKs [Snf1 (sucrose non-fermenting-1)-related protein kinases] function as an example, but drawing also on the related signalling systems involving Snf1 itself in fungi and AMPK (AMP-activated protein kinase) in animals. In plants, the SnRK family comprises not only SnRK1, but also two other subfamilies, SnRK2 and SnRK3, with a total of 38 members in the model plant Arabidopsis. This may have occurred to enable linking of metabolic and stress signalling. It is concluded that signalling pathways comprise multiple levels not to allow for signal amplification, but to enable linking between pathways to form networks in which key protein kinases, phosphatases and target transcription factors represent hubs on/from which multiple pathways converge and emerge.
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April 2009
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Review Article|
March 27 2009
Snf1-related protein kinases (SnRKs) act within an intricate network that links metabolic and stress signalling in plants
Nigel G. Halford;
Nigel G. Halford
1
1Plant Science Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, U.K.
1To whom correspondence should be addressed (email nigel.halford@bbsrc.ac.uk).
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Sandra J. Hey
Sandra J. Hey
1Plant Science Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, U.K.
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Publisher: Portland Press Ltd
Received:
December 19 2008
Revision Received:
January 30 2009
Accepted:
February 02 2009
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2009 Biochemical Society
2009
Biochem J (2009) 419 (2): 247–259.
Article history
Received:
December 19 2008
Revision Received:
January 30 2009
Accepted:
February 02 2009
Citation
Nigel G. Halford, Sandra J. Hey; Snf1-related protein kinases (SnRKs) act within an intricate network that links metabolic and stress signalling in plants. Biochem J 15 April 2009; 419 (2): 247–259. doi: https://doi.org/10.1042/BJ20082408
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