Editing Succinic acid (section)

=== GABA shunt ===
Succinate is the re-entry point for the [[Gamma-Aminobutyric acid|gamma-aminobutyric acid]] (GABA) shunt into the TCA cycle, a closed cycle which synthesizes and recycles GABA.<ref name=BasicNeurochemTextChapter>{{cite book|last1=Olsen|first1=Richard W|last2=DeLorey|first2=Timothy M|editor1-last=Siegel|editor1-first=GJ|editor2-last=Agranoff|editor2-first=BW|editor3-last=Albers|editor3-first=RW |display-editors=etal |title=Basic Neurochemistry: Molecular, Cellular and Medical Aspects|date=1999|publisher=Lippincott-Raven|location=Philadelphia|edition=6th|chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK27979/|chapter=GABA Synthesis, Uptake and Release}}</ref> The GABA shunt serves as an alternate route to convert [[Alpha-Ketoglutaric acid|alpha-ketoglutarate]] into succinate, bypassing the TCA cycle intermediate succinyl-CoA and instead producing the intermediate GABA. Transamination and subsequent decarboxylation of alpha-ketoglutarate leads to the formation of GABA. GABA is then metabolized by [[GABA transaminase]] to [[succinic semialdehyde]]. Finally, succinic semialdehyde is oxidized by [[succinic semialdehyde dehydrogenase]] (SSADH) to form succinate, re-entering the TCA cycle and closing the loop. Enzymes required for the GABA shunt are expressed in neurons, glial cells, macrophages and pancreatic cells.<ref name=BasicNeurochemTextChapter/>
[[File:Integrated Diagram of Succinate Biofunctionality .png|thumb|540x540px|Biological roles of succinate. Inside the mitochondria, succinate serves as an intermediate in multiple metabolic pathways and contributes to the generation of ROS. Outside the mitochondria, succinate functions as both an intracellular and extracellular signaling molecule. OOA=oxaloacetate; a-KG=alpha ketoglutarate; GLUT= Glutamate; GABA = gamma-aminobutyric acid; SSA=Succinic semialdehyde; PHD= prolyl hydroxylase; HIF-1a=hypoxia inducible factor 1a; TET= Ten-eleven Translocation Enzymes; JMJD3= Histone demethylase Jumonji D3]]