{PDOC51473}
{PS51473; GNK2}
{BEGIN}
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* Gnk2-homologous domain profile *
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Ginkbilobin-2 (Gnk2) is an antifungal protein found in the endosperm of Ginkgo
seeds, which  inhibits  the  growth  of phytopathogenic fungi such as Fusarium
oxysporum. Gnk2  has  considerable homology (~85%) to embryo-abundant proteins
(EAP) from  the gymnosperms Picea abies and P. glauca. Plant EAP are expressed
in the  late  stage  of seed maturation and are involved in protection against
environmental stresses  such  as  drought. The sequence of Gnk2 is also 28-31%
identical to  the  extracellular domain of cysteine-rich receptor-like kinases
(CRK) from the angiosperm Arabidopsis. The CRK members are induced by pathogen
infection and treatment with reactive oxygen species or salicylic acid and are
involved in  the  hypersensitive  reaction,  which  is  a  typical  system  of
programmed cell death. In addition, there are at least 60 genes in Arabidopsis
encoding the  cysteine-rich  secreted  proteins (CRSP) with an Gnk2-homologous
domain. Therefore,  the proteins with a Gnk2-homologous domain are regarded as
one of  the  largest protein superfamilies, although the role of the conserved
Gnk2-homologous domain remains unclear [1,2].

The Gnk2-homologous  domain  is  composed  of  two  alpha-helices  and  a five
stranded beta-sheet,  which forms a compact single-domain architecture with an
alpha+beta-fold (see   <PDB:3A2E>).   It  contains  a  C-X(8)-C-X(2)-C  motif.
Cysteine residues  form  three intramolecular disulfide bridges: C1-C5, C2-C3,
and C4-C6 [1].

The profile we developed covers the entire Gnk2-homologous domain.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: January 2010 / First entry.

[ 1] Miyakawa T., Miyazono K., Sawano Y., Hatano K., Tanokura M.
     "Crystal structure of ginkbilobin-2 with homology to the extracellular
     domain of plant cysteine-rich receptor-like kinases."
     Proteins 77:247-251(2009).
     PubMed=19603485; DOI=10.1002/prot.22494
[ 2] Chen Z.
     "A superfamily of proteins with novel cysteine-rich repeats."
     Plant Physiol. 126:473-476(2001).
     PubMed=11402176

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