{PDOC51159}
{PS51159; CBM21}
{BEGIN}
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* CBM21 (carbohydrate binding type-21) domain profile *
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The  carbohydrate  binding  type-21  or  CBM21  domain  is a 90-130 amino acid
carbohydrate  binding domain. The domain is named after proteins classified in
carbohydrate-binding   module   (CBM)   family  21  and  is  sometimes  called
starch-binding  domain  (SBD)  [E1,1].  The  CBM21  domain  occurs  in several
eukaryotic  proteins  implicated in glycogen metabolism. A glucoamylase active
site  region (see <PDOC00646>) [E2] or alpha amylase catalytic domain [E3] can
occur  C-terminal  to  the  CBM21  domain. The CBM21 domain of Rhizopus oryzae
glucoamylase  can bind to raw starch. Most conserved residues are located in a
region  with  a length of 35 in the N-terminal part [2] and in a 15-25 residue
motif II at the C-terminus of the domain [2-4].

Some proteins known to contain a CBM21 domain:

 - Mammalian protein phosphatase 1 (PP1) regulatory subunit 3A, which seems to
   target PP1 to glycogen.
 - Mammalian  protein phosphatase 1 binding protein PTG, which binds the 3 key
   enzymes  for  the  regulation of glycogen metabolism: phosphorylase kinase,
   phosphorylase A and glycogen synthase.
 - Yeast  protein  phosphatase  1 regulatory subunits GAC1 and PIG1, which are
   regulators of glycogen synthase.
 - Yeast GLC7-interacting protein 2 (GIP2), which interacts with the catalytic
   subunit (GLC7) of PP1.
 - Yeast protein 2 interacting with GSY2 (PIG2), which interacts with glycogen
   synthase 2 (GSY2), a nutritionally regulated form.
 - Rhizopus  oryzae  glucoamylase, which binds and hydrolyzes granular starch.
   R.  oryzae  is  a  fungus  from  e.g.  decaying  vegetables  and  it causes
   mucormycosis.

The  profile we developed covers the entire CBM21 domain.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Last update: November 2005 / First entry.

[ 1] Rodriguez-Sanoja R., Oviedo N., Sanchez S.
     "Microbial starch-binding domain."
     Curr. Opin. Microbiol. 8:260-267(2005).
     PubMed=15939348; DOI=10.1016/j.mib.2005.04.013
[ 2] Cheng C., Huang D., Roach P.J.
     "Yeast PIG genes: PIG1 encodes a putative type 1 phosphatase subunit
     that interacts with the yeast glycogen synthase Gsy2p."
     Yeast 13:1-8(1997).
     PubMed=9046081; DOI=10.1002/(SICI)1097-0061(199701)13:1<1::AID-YEA49>3.0.CO;2-F
[ 3] Printen J.A., Brady M.J., Saltiel A.R.
     "PTG, a protein phosphatase 1-binding protein with a role in glycogen
     metabolism."
     Science 275:1475-1478(1997).
     PubMed=9045612
[ 4] Machovic M., Svensson B., Ann Macgregor E., Janecek S.
     "A new clan of CBM families based on bioinformatics of starch-binding
     domains from families CBM20 and CBM21."
     FEBS J. 272:5497-5513(2005).
     PubMed=16262690; DOI=10.1111/j.1742-4658.2005.04942.x
[E1] http://www.cazy.org/CBM21.html
[E2] http://www.cazy.org/GH13.html
[E3] http://www.cazy.org/GH15.html

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