Guanylate kinase (EC 188.8.131.52) (GK)  catalyzes the ATP-dependent
phosphorylation of GMP into GDP. It is essential for recycling GMP and
indirectly, cGMP. In prokaryotes (such as Escherichia coli), lower eukaryotes
(such as yeast) and in vertebrates, GK is a highly conserved monomeric
protein of about 200 amino acids. GK has been shown [2,3,4] to be structurally
similar to the following proteins:
Protein A57R (or SalG2R) from various strains of Vaccinia virus. This
protein is highly similar to GK, but contains a frameshift mutation in the
N-terminal section and could therefore be inactive in that virus.
The following proteins are characterized by the presence in their sequence of
one or more copies of the DHR domain, a SH3 domain (see <PDOC50002> as well as
a C-terminal GK-like domain, these protein are collectively termed MAGUKs
(membrane-associated guanylate kinase homologs) :
Drosophila lethal(1)discs large-1 tumor suppressor protein (gene dlg1).
This protein is associated with septate junctions in developing flies and
defects in the dlg1 gene cause neoplastic overgrowth of the imaginal disks.
Mammalian tight junction protein Zo-1.
A family of mammalian synaptic proteins that seem to interact with the
cytoplasmic tail of NMDA receptor subunits. This familly currently consist
of SAP90/PSD-95, CHAPSYN-110/PSD-93, SAP97/DLG1 and SAP102.
Vertebrate 55 Kd erythrocyte membrane protein (p55). p55 is a palmitoylated,
membrane-associated protein of unknown function.
Caenorhabditis elegans protein lin-2, which may play a structural role in
the induction of the vulva.
Rat protein CASK.
Human protein DLG2.
Human protein DLG3.
There is an ATP-binding site (P-loop) in the N-terminal section of GK. This
region is not conserved in the GK-like domain of the above proteins which are
therefore unlikely to be kinases. However these proteins retain the residues
known, in GK, to be involved in the binding of GMP. As a signature pattern we
selected a highly conserved region that contains two arginine and a tyrosine
which are involved in GMP-binding.
December 2004 / Pattern and text revised.
PROSITE methods (with tools and information) covered by this documentation:
Stehle T., Schulz G.E.
Refined structure of the complex between guanylate kinase and its substrate GMP at 2.0 A resolution.
PROSITE is copyright. It is produced by the SIB Swiss Institute
Bioinformatics. There are no restrictions on its use by non-profit
institutions as long as its content is in no way modified. Usage by and
for commercial entities requires a license agreement. For information
about the licensing scheme send an email to
or see: prosite_license.html.