{PDOC00101}
{PS00110; PYRUVATE_KINASE}
{BEGIN}
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* Pyruvate kinase active site signature *
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Pyruvate kinase (EC 2.7.1.40) (PK) [1] catalyzes the final step in glycolysis,
the conversion  of  phosphoenolpyruvate  to  pyruvate   with  the  concomitant
phosphorylation of ADP to ATP.  PK requires  both magnesium and potassium ions
for its activity.  PK is found in all  living organisms.  In vertebrates there
are four, tissues  specific, isozymes:  L (liver),  R (red cells), M1 (muscle,
heart, and brain), and M2 (early fetal tissues). In Escherichia coli there are
two isozymes: PK-I (gene pykF) and PK-II (gene pykA).  All PK isozymes seem to
be tetramers of identical subunits of about 500 amino acid residues.

As a signature pattern for PK we  selected a  conserved region that includes a
lysine residue which seems to be the acid/base  catalyst  responsible  for the
interconversion  of  pyruvate and  enolpyruvate, and a  glutamic  acid residue
implicated in the binding of the magnesium ion.

-Consensus pattern: [LIVAC]-x-[LIVM](2)-[SAPCV]-K-[LIV]-E-[NKRST]-x-[DEQHS]-
                    [GSTA]-[LIVM]
                    [K is the active site residue]
                    [E is a magnesium ligand]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: 2.
-Last update: July 1999 / Pattern and text revised.

[ 1] Muirhead H.
     "Isoenzymes of pyruvate kinase."
     Biochem. Soc. Trans. 18:193-196(1990).
     PubMed=2379684

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