MetaCyc Enzyme: phosphoenolpyruvate carboxylase

Gene: pep1 Accession Number: G-41 (MetaCyc)

Synonyms: pepczm1, C4Ppc1, PEPC, C4PEPC

Species: Zea mays

Subunit composition of phosphoenolpyruvate carboxylase = [Pep1]4
         phosphoenolpyruvate carboxylase = Pep1

There are at least three isozymes of phosphoenolpyruvate carboxylase (PEPC) in maize, the C3 form (involved in C3 photosynthesis, Calvin cycle), the C4 form (involved in C4 photosynthesis, described here), and the root form. The C4 PEPC is located in the cytosol of mesophyll cells of leaves and is encoded by the maize pep1 gene. The C4 PEPC is reversibly regulated by phosphorylation. It is phosphorylated during the day time to become a more active form and dephosphorylated during the night to a less active form.
pep1 (MaizeDB), or pepczm1 (GenBank) encodes the C4 form PEPC.

Citations: [Ueno00, Matsumura99a]

Gene Citations: [Schaffner92, Taniguchi00]

Locations: cytoplasm

Molecular Weight of Polypeptide: 100 kD (experimental)

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

GO Terms:

Cellular Component: GO:0005737 - cytoplasm


Enzymatic reaction of: phosphoenolpyruvate carboxylase

EC Number:

oxaloacetate + phosphate <=> phosphoenolpyruvate + hydrogen carbonate

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

This reaction is reversible.

In Pathways: C4 photosynthetic carbon assimilation cycle, NADP-ME type , C4 photosynthetic carbon assimilation cycle, PEPCK type

The phosphoenolpyruvate-Mg complex is the preferred substrate of the C4 PEPC.

Citations: [RodriguezSotres90, Matsumura99a]

Cofactors or Prosthetic Groups: Mg2+

Activators (Allosteric): β-D-glucose 6-phosphate , glycine

Inhibitors (Allosteric): (S)-malate , L-aspartate


Matsumura99a: Matsumura H, Nagata T, Terada M, Shirakata S, Inoue T, Yoshinaga T, Ueno Y, Saze H, Izui K, Kai Y (1999). "Crystallization and preliminary x-ray diffraction studies of C4-form phosphoenolpyruvate carboxylase from maize." Acta Crystallogr D Biol Crystallogr 1999;55(11);1937-8. PMID: 10531501

RodriguezSotres90: Rodriguez-Sotres R, Munoz-Clares RA (1990). "Kinetic evidence of the existence of a regulatory phosphoenolpyruvate binding site in maize leaf phosphoenolpyruvate carboxylase." Arch Biochem Biophys 1990;276(1);180-90. PMID: 2297221

Schaffner92: Schaffner AR, Sheen J (1992). "Maize C4 photosynthesis involves differential regulation of phosphoenolpyruvate carboxylase genes." Plant J 1992;2(2);221-32. PMID: 1302051

Taniguchi00: Taniguchi M, Izawa K, Ku MS, Lin JH, Saito H, Ishida Y, Ohta S, Komari T, Matsuoka M, Sugiyama T (2000). "Binding of cell type-specific nuclear proteins to the 5'-flanking region of maize C4 phosphoenolpyruvate carboxylase gene confers its differential transcription in mesophyll cells." Plant Mol Biol 2000;44(4);543-57. PMID: 11197328

Ueno00: Ueno Y, Imanari E, Emura J, Yoshizawa-Kumagaye K, Nakajima K, Inami K, Shiba T, Sakakibara H, Sugiyama T, Izui K (2000). "Immunological analysis of the phosphorylation state of maize C4-form phosphoenolpyruvate carboxylase with specific antibodies raised against a synthetic phosphorylated peptide." Plant J 2000;21(1);17-26. PMID: 10652147

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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