Editing Aspartate transaminase (section)

==Isoenzymes==
Two isoenzymes are present in a wide variety of eukaryotes.  In humans:{{cn|date=November 2021}}
* [[GOT1]]/cAST, the [[cytosol]]ic isoenzyme derives mainly from [[red blood cell]]s and [[heart]].
* [[GOT2]]/mAST, the [[Mitochondrion|mitochondrial]] isoenzyme is present predominantly in liver.

These isoenzymes are thought to have evolved from a common ancestral AST via gene duplication, and they share a sequence homology of approximately 45%.<ref name="pmid2197992">{{Cite journal |vauthors=Hayashi H, Wada H, Yoshimura T, Esaki N, Soda K |year=1990 |title=Recent topics in pyridoxal 5'-phosphate enzyme studies |journal=Annual Review of Biochemistry |volume=59 |pages=87–110 |doi=10.1146/annurev.bi.59.070190.000511 |pmid=2197992}}</ref>

AST has also been found in a number of microorganisms, including ''[[E. coli]]'', ''[[Haloferax|H. mediterranei]]'',<ref name="pmid1909112">{{Cite journal |vauthors=Muriana FJ, Alvarez-Ossorio MC, Relimpio AM |date=August 1991 |title=Purification and characterization of aspartate aminotransferase from the halophile archaebacterium Haloferax mediterranei |journal=The Biochemical Journal |volume=278 |issue=1 |pages=149–154 |doi=10.1042/bj2780149 |pmc=1151461 |pmid=1909112}}</ref> and ''[[Thermus thermophilus|T. thermophilus]]''.<ref name="pmid8907187">{{Cite journal |vauthors=Okamoto A, Kato R, Masui R, Yamagishi A, Oshima T, Kuramitsu S |date=January 1996 |title=An aspartate aminotransferase from an extremely thermophilic bacterium, Thermus thermophilus HB8 |journal=Journal of Biochemistry |volume=119 |issue=1 |pages=135–144 |doi=10.1093/oxfordjournals.jbchem.a021198 |pmid=8907187}}</ref> In ''E. coli'', the enzyme is encoded by the ''aspC''gene and has also been shown to exhibit the activity of an [[aromatic-amino-acid transaminase]] ({{EC number|2.6.1.57}}).<ref name="pmid15983">{{Cite journal |vauthors=Gelfand DH, Steinberg RA |date=April 1977 |title=Escherichia coli mutants deficient in the aspartate and aromatic amino acid aminotransferases |journal=Journal of Bacteriology |volume=130 |issue=1 |pages=429–440 |doi=10.1128/JB.130.1.429-440.1977 |pmc=235221 |pmid=15983}}</ref>