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Phosphagen (guanidino) kinases, including creatine kinase (CK), arginine
kinase (AK), taurocyamine kinase (TK), lombricine kinase (LK), glycocyamine
kinase (GK), and hypotaurocyamine kinase (HTK), are enzymes that catalyze the
reversible transfer of the γ-phosphoryl group of adenosine triphosphate
(ATP) to naturally occuring guanidino compounds such as creatine, arginine,
yelding adenosine diphosphate (ADP) and a phosphorylated guanidine typically
referred to as phosphagen (phosphocreatine, phosphoarginine and etc). Members
of this enzyme family play a key role in animals as ATP-buffering systems in
cells that display high and variable rates of ATP turnover. Phosphagen kinases
have been found in all animal species and in some protozoa, such as
trypanosomes, choanoflagellates, and the ciliates, Paramecium tetraurelia,
Paramecium caudatum, and Tetrahymena. Eukaryotic phosphagen kinases consist of
a small, ~100-residue, α-helical N-terminal domain and a larger, 250+-residue, C-terminal α/β saddle domain in which many key residues
involved in catalysis are found (see <PDB:3L2E>). The N-terminal domain
undergoes significant conformational movements during catalysis, closing down
on the catalytic pocket. It is involved in dimer formation. Bacterial
phosphagen kinases have the large C-terminal domain seen in eukaryotic
phosphagen kinases but lack the N-terminal domain [1,2,3,4].
A cysteine residue is implicated in the catalytic activity of these enzymes.
The region around this active site residue is highly conserved and can be used
as a signature pattern. We also developed two profiles, which cover
respectively the entire phosphagen kinase N- and C-terminal domains.
December 2010 / Text revised; profiles added.
PROSITE methods (with tools and information) covered by this documentation:
Tanaka K., Uda K., Shimada M., Takahashi K., Gamou S., Ellington W.R., Suzuki T.
Evolution of the cytoplasmic and mitochondrial phosphagen kinases unique to annelid groups.
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