PATHWAY: xla00020 Help
Entry
Name
Citrate cycle (TCA cycle) - Xenopus laevis (African clawed frog)
Description
The citrate cycle (TCA cycle, Krebs cycle) is an important aerobic pathway for the final steps of the oxidation of carbohydrates and fatty acids. The cycle starts with acetyl-CoA, the activated form of acetate, derived from glycolysis and pyruvate oxidation for carbohydrates and from beta oxidation of fatty acids. The two-carbon acetyl group in acetyl-CoA is transferred to the four-carbon compound of oxaloacetate to form the six-carbon compound of citrate. In a series of reactions two carbons in citrate are oxidized to CO2 and the reaction pathway supplies NADH for use in the oxidative phosphorylation and other metabolic processes. The pathway also supplies important precursor metabolites including 2-oxoglutarate. At the end of the cycle the remaining four-carbon part is transformed back to oxaloacetate. According to the genome sequence data, many organisms seem to lack genes for the full cycle [MD:
M00009 ], but contain genes for specific segments [MD:
M00010 M00011 ].
Class
Metabolism; Carbohydrate metabolism
BRITE hierarchy
Pathway map
Ortholog table
Module
xla_M00010 Citrate cycle, first carbon oxidation, oxaloacetate => 2-oxoglutarate [PATH:xla00020 ]
xla_M00011 Citrate cycle, second carbon oxidation, 2-oxoglutarate => oxaloacetate [PATH:xla00020 ]
Other DBs
Organism
Xenopus laevis (African clawed frog) [GN:
xla ]
Gene
380013 idh2.S; isocitrate dehydrogenase 2 (NADP+), mitochondrial S homeolog [KO:K00031 ] [EC:1.1.1.42 ]
108711283 idh3a.L; isocitrate dehydrogenase [NAD] subunit alpha, mitochondrial isoform X1 [KO:K00030 ] [EC:1.1.1.41 ]
447370 ogdhl.L; 2-oxoglutarate dehydrogenase-like, mitochondrial precursor [KO:K00164 ] [EC:1.2.4.2 ]
380395 dlst.S; dihydrolipoyllysine-residue succinyltransferase component of 2-oxoglutarate dehydrogenase complex, mitochondrial [KO:K00658 ] [EC:2.3.1.61 ]
108698673 dlst.L; dihydrolipoyllysine-residue succinyltransferase component of 2-oxoglutarate dehydrogenase complex, mitochondrial [KO:K00658 ] [EC:2.3.1.61 ]
398946 sdha.L; succinate dehydrogenase [ubiquinone] flavoprotein subunit A, mitochondrial precursor [KO:K00234 ] [EC:1.3.5.1 ]
380463 sdha.S; succinate dehydrogenase [ubiquinone] flavoprotein subunit B, mitochondrial precursor [KO:K00234 ] [EC:1.3.5.1 ]
379939 sdhb.S; succinate dehydrogenase [ubiquinone] iron-sulfur subunit, mitochondrial precursor [KO:K00235 ] [EC:1.3.5.1 ]
108696840 sdhb.L; succinate dehydrogenase [ubiquinone] iron-sulfur subunit, mitochondrial-like [KO:K00235 ] [EC:1.3.5.1 ]
108700387 sdhc.S; succinate dehydrogenase cytochrome b560 subunit, mitochondrial [KO:K00236 ]
496372 sdhd.L; succinate dehydrogenase [ubiquinone] cytochrome b small subunit B, mitochondrial [KO:K00237 ]
494586 sdhd.S; succinate dehydrogenase [ubiquinone] cytochrome b small subunit A, mitochondrial [KO:K00237 ]
398872 mdh1.S; malate dehydrogenase 1 S homeolog, cytoplasmic isoform mdh1 [KO:K00025 ] [EC:1.1.1.37 ]
399424 pck2.L; phosphoenolpyruvate carboxykinase 2 (mitochondrial) L homeolog [KO:K01596 ] [EC:4.1.1.32 ]
121400462 pyruvate dehydrogenase E1 component subunit alpha, somatic form, mitochondrial-like isoform X1 [KO:K00161 ] [EC:1.2.4.1 ]
121400749 pyruvate dehydrogenase E1 component subunit alpha, somatic form, mitochondrial-like [KO:K00161 ] [EC:1.2.4.1 ]
121400742 pyruvate dehydrogenase E1 component subunit alpha, somatic form, mitochondrial-like [KO:K00161 ] [EC:1.2.4.1 ]
108705521 dihydrolipoyllysine-residue acetyltransferase component of pyruvate dehydrogenase complex, mitochondrial isoform X1 [KO:K00627 ] [EC:2.3.1.12 ]
Compound
C05125 2-(alpha-Hydroxyethyl)thiamine diphosphate
C05381 3-Carboxy-1-hydroxypropyl-ThPP
C15972 Enzyme N6-(lipoyl)lysine
C15973 Enzyme N6-(dihydrolipoyl)lysine
C16254 [Dihydrolipoyllysine-residue succinyltransferase] S-succinyldihydrolipoyllysine
C16255 [Dihydrolipoyllysine-residue acetyltransferase] S-acetyldihydrolipoyllysine
Reference
Authors
Nishizuka Y (ed).
Title
[Metabolic Maps] (In Japanese)
Journal
Tokyo Kagaku Dojin (1980)
Reference
Authors
Nishizuka Y, Seyama Y, Ikai A, Ishimura Y, Kawaguchi A (eds).
Title
[Cellular Functions and Metabolic Maps] (In Japanese)
Journal
Tokyo Kagaku Dojin (1997)
Reference
Authors
Michal G.
Title
Biochemical Pathways
Journal
Wiley (1999)
Related pathway
xla00053 Ascorbate and aldarate metabolism
xla00250 Alanine, aspartate and glutamate metabolism
xla00280 Valine, leucine and isoleucine degradation
xla00630 Glyoxylate and dicarboxylate metabolism
KO pathway
LinkDB
All DBs