PXLP-GCAT dimer ligates CoASH to 2A-3OB to form Gly and Ac-CoA

Stable Identifier
R-HSA-6798345
Type
Reaction
Species
Homo sapiens
Compartment
Locations in the PathwayBrowser
General
SVG |   | PPTX  | SBGN
Click the image above or here to open this reaction in the Pathway Browser
The layout of this reaction may differ from that in the pathway view due to the constraints in pathway layout

The degradation of L-threonine to glycine in both prokaryotes and eukaryotes takes place through a two-step biochemical pathway. In the second step, mitochondrial 2-amino-3-ketobutyrate coenzyme A ligase (GCAT, aka KBL) catalyses the reaction between 2-amino-3-oxobutanoate (2A-3OBU) and coenzyme A (CoA-SH) to form glycine (Gly) and acetyl-CoA (Ac-CoA) (Edgar & Polak 2000). GCAT resides on the mitochondrial inner membrane and requires pyridoxal 5-phosphate (PXLP) as cofactor. It is strongly expressed in heart, brain, liver and pancreas. Dimeric GCAT:PXLP is thought to exist on the mitochondrial inner membrane in complex with tetrameric L-threonine 3-dehydrogenase (TDH), the first enzyme in this pathway (Tressel et al. 1986). With these two enzymes located together, it stops the rapid and spontaneous decarboxylation of 2A-3OBU to aminoacetone and carbon dioxide and instead, results in glycine formation.

Literature References
PubMed ID Title Journal Year
3536927 Interaction between L-threonine dehydrogenase and aminoacetone synthetase and mechanism of aminoacetone production

Davis, L, Zieske, LR, Thompson, R, Menendez, MI, Tressel, T

J. Biol. Chem. 1986
10712613 Molecular cloning of the human and murine 2-amino-3-ketobutyrate coenzyme A ligase cDNAs

Edgar, AJ, Polak, JM

Eur. J. Biochem. 2000
Participants
Participates
Catalyst Activity

CoA-ligase activity of PXLP-GCAT dimer:TDH tetramer [mitochondrial inner membrane]

Authored
Reviewed
Created
Cite Us!