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PEP carboxylase kinase is a novel protein kinase controlled at the level of expression
Author(s) -
Nimmo Hugh G.,
Fontaine Véronique,
Hartwell James,
Jenkins Gareth I.,
Nimmo Gillian A.,
Wilkins Malcolm B.
Publication year - 2001
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.2001.00155.x
Subject(s) - phosphoenolpyruvate carboxylase , pyruvate carboxylase , protein kinase a , biochemistry , biology , cyclin dependent kinase 2 , kinase , acetyl coa carboxylase , microbiology and biotechnology , enzyme
Summary Phosphoenolpyruvate (PEP) carboxylase plays a number of key roles in the central metabolism of higher plants. The enzyme is regulated by reversible phosphorylation in response to a range of signals in many different plant tissues. The data discussed here illustrate several novel features of this system. The phosphorylation state of PEP carboxylase is controlled largely by the activity of PEP carboxylase kinase. This enzyme comprises a protein kinase catalytic domain with no regulatory regions. In many systems it is controlled at the level of expression. In C 4 plants, expression of PEP carboxylase kinase is light‐regulated and involves changes in cytosolic pH, InsP 3 and Ca 2+ levels. Expression of PEP carboxylase kinase in CAM plants is regulated by a circadian oscillator, perhaps via metabolite control. Some plants contain multiple PEP carboxylase kinase genes, probably with different expression patterns and roles. A newly discovered PEP carboxylase kinase inhibitor protein might facilitate the net dephosphorylation of PEP carboxylase under conditions in which flux through this enzyme is not required.