{PDOC50801}
{PS50801; STAS}
{BEGIN}
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* STAS domain profile *
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The STAS  domain  is  found  in  the  C-terminal  cytoplasmic  part  of  anion
transporters from  eukaryotes  and  many bacteria, as well as in the bacterial
anti-sigma-factor antagonists  (ASAs).   It   was  named  STAS  after  sulfate
transporters and anti-sigma-factor antagonist [1].

Malfunctions in  members  of  the  SLC26A  family  of  anion  transporters are
involved in  three  human diseases: diastrophic dysplasia/achondrogenesis type
1B (DTDST),  Pendred's  syndrome (PDS) and congenital chloride diarrhea (CLD).
These proteins contain 12 transmembrane helices followed by a cytoplasmic STAS
domain at  the  C-terminus.  The  importance  of  the  STAS  domain  in  these
transporters is  illustrated by the fact that a number of mutations in PDS and
DTDST map to it [1].

The activity  of  bacterial  sigma  transcription  factors  is controlled by a
regulatory cascade involving  an anti-sigma-factor, the ASA and a phosphatase.
The antisigma-factor  binds  to sigma and holds it in an inactive complex. The
ASA can  also interact with the anti-sigma-factor, allowing the release of the
active sigma  factor.  As  the  anti-sigma-factor is a protein kinase,  it can
phosphorylate the  anti-sigma antagonist  on a conserved serine residue of the
STAS domain.  This phosphorylation inactivates the ASA that can be reactivated
through dephosphorylation  by  a phosphatase [1,2]. The STAS domain of the ASA
SpoIIAA binds  GTP  and  ATP  and  possesses  a  weak  NTPase activity. Strong
sequence conservation suggests that the STAS domain could possess general NTP-
binding activity  and  it has been proposed that the NTPs are likely to elicit
specific conformational  changes  in  the  STAS  domain through binding and/or
hydrolysis [1].

Resolution of the solution structure of the ASA SpoIIAA from Bacillus subtilis
(see <PDB:1AUZ>)  has  shown  that the STAS domain consists of a four-stranded
beta-sheet and  four  alpha  helices.  The  STAS domain forms a characteristic
alpha-helical handle-like structure [1,3].

Some proteins known to contain a STAS domain are listed below:

 - Members of the SLC26 family of anion transporters.
 - Anti-sigma-factor antagonists such as Bacillus subtilis SpoIIAA [2].
 - Blue-light photoreceptor (Phototropin homolog) from Bacillus subtilis.
 - Hypothetical protein K12G11.1 from Caenorhabditis elegans.
 - Hypothetical protein SPCC320.05 from fission yeast.

The profile we developed covers the entire STAS domain.

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: April 2002 / First entry.

[ 1] Aravind L., Koonin E.V.
     "The STAS domain - a link between anion transporters and
     antisigma-factor antagonists."
     Curr. Biol. 10:R53-R55(2000).
     PubMed=10662676
[ 2] Feucht A., Daniel R.A., Errington J.
     "Characterization of a morphological checkpoint coupling cell-specific
     transcription to septation in Bacillus subtilis."
     Mol. Microbiol. 33:1015-1026(1999).
     PubMed=10476035
[ 3] Kovacs H., Comfort D., Lord M., Campbell I.D., Yudkin M.D.
     "Solution structure of SpoIIAA, a phosphorylatable component of the
     system that regulates transcription factor sigmaF of Bacillus
     subtilis."
     Proc. Natl. Acad. Sci. U.S.A. 95:5067-5071(1998).
     PubMed=9560229

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