{PDOC00289}
{PS00324; ASPARTOKINASE}
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* Aspartokinase signature *
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Aspartokinase (EC   2.7.2.4)   (AK)   [1]  catalyzes  the  phosphorylation  of
aspartate.  The product of this  reaction can then be used in the biosynthesis
of lysine or in the pathway leading to  homoserine, which participates in  the
biosynthesis of threonine, isoleucine and methionine.

In Escherichia coli, there are three different isozymes  which differ in their
sensitivity to  repression and inhibition by Lys, Met and Thr. AK1 (gene thrA)
and AK2  (gene  metL)  are  bifunctional  enzymes  which both consist of an N-
terminal AK  domain and a  C-terminal  homoserine dehydrogenase domain. AK1 is
involved in  threonine  biosynthesis and AK2, in that of methionine. The third
isozyme, AK3  (gene lysC), is monofunctional and involved in lysine synthesis.
In yeast, there is a single isozyme of AK (gene HOM3).

As a  signature  pattern for AK, we selected a conserved region located in the
N-terminal extremity.

-Consensus pattern: [LIVM]-x-K-[FY]-G-G-[ST]-[SC]-[LIVM]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: 1.
-Last update: November 1995 / Pattern and text revised.

[ 1] Rafalski J.A., Falco S.C.
     "Structure of the yeast HOM3 gene which encodes aspartokinase."
     J. Biol. Chem. 263:2146-2151(1988).
     PubMed=2892836

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