{PDOC00190}
{PS00216; SUGAR_TRANSPORT_1}
{PS00217; SUGAR_TRANSPORT_2}
{BEGIN}
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* Sugar transport proteins signatures *
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In mammalian  cells  the uptake of glucose is  mediated by a family of closely
related transport  proteins which are called the glucose transporters [1,2,3].
At least  seven of these transporters are  currently  known to exist (in Human
they are encoded by the GLUT1 to GLUT7 genes).

These integral membrane proteins  are  predicted  to  comprise twelve membrane
spanning domains.  The  glucose  transporters show sequence similarities [4,5]
with a number of other sugar or  metabolite transport  proteins  listed  below
(references are only provided for recently determined sequences).

 - Escherichia coli arabinose-proton symport (araE).
 - Escherichia coli galactose-proton symport (galP).
 - Escherichia coli and  Klebsiella pneumoniae  citrate-proton  symport  (also
   known as citrate utilization determinant) (gene cit).
 - Escherichia coli alpha-ketoglutarate permease (gene kgtP).
 - Escherichia coli proline/betaine transporter (gene proP) [6].
 - Escherichia coli xylose-proton symport (xylE).
 - Zymomonas mobilis glucose facilitated diffusion protein (gene glf).
 - Yeast high and low affinity glucose transport proteins (genes SNF3, HXT1 to
   HXT14).
 - Yeast galactose transporter (gene GAL2).
 - Yeast maltose permeases (genes MAL3T and MAL6T).
 - Yeast myo-inositol transporters (genes ITR1 and ITR2).
 - Yeast carboxylic acid transporter protein homolog JEN1.
 - Yeast inorganic phosphate transporter (gene PHO84).
 - Kluyveromyces lactis lactose permease (gene LAC12).
 - Neurospora crassa quinate transporter (gene Qa-y),  and Emericella nidulans
   quinate permease (gene qutD).
 - Chlorella hexose carrier (gene HUP1).
 - Arabidopsis thaliana glucose transporter (gene STP1).
 - Spinach sucrose transporter.
 - Leishmania donovani transporters D1 and D2.
 - Leishmania enriettii probable transport protein (LTP).

 - Yeast hypothetical proteins YBR241c, YCR98c and YFL040w.
 - Caenorhabditis elegans hypothetical protein ZK637.1.
 - Escherichia coli hypothetical proteins yabE, ydjE and yhjE.
 - Haemophilus influenzae hypothetical proteins HI0281 and HI0418.
 - Bacillus subtilis hypothetical proteins yxbC and yxdF.

It has been suggested [4]  that these transport proteins have evolved from the
duplication of  an  ancestral  protein  with  six  transmembrane regions, this
hypothesis is based on the conservation of two G-R-[KR] motifs.  The first one
is located  between  the second and third transmembrane domains and the second
one between transmembrane domains 8 and 9.

We have developed  two patterns  to  detect this family of proteins. The first
pattern is based on the G-R-[KR] motif; but because this motif is too short to
be  specific to  this  family  of  proteins, we  have derived a pattern from a
larger region  centered on the  second copy of this motif.  The second pattern
is based on a number of conserved residues which are located at the end of the
fourth transmembrane  segment  and in the short loop region between the fourth
and fifth segments.

-Consensus pattern: [LIVMSTAG]-[LIVMFSAG]-{SH}-{RDE}-[LIVMSA]-[DE]-{TD}-
                    [LIVMFYWA]-G-R-[RK]-x(4,6)-[GSTA]
-Sequences known to belong to this class detected by the pattern: the majority
 of transporters with 23 exceptions.
-Other sequence(s) detected in Swiss-Prot: 53.

-Consensus pattern: [LIVMF]-x-G-[LIVMFA]-{V}-x-G-{KP}-x(7)-[LIFY]-x(2)-[EQ]-
                    x(6)-[RK]
-Sequences known to belong to this class detected by the pattern: the majority
 of transporters with 20 exceptions.
-Other sequence(s) detected in Swiss-Prot: 67.

-Last update: April 2006 / Patterns revised.

[ 1] Silverman M.
     "Structure and function of hexose transporters."
     Annu. Rev. Biochem. 60:757-794(1991).
     PubMed=1883208; DOI=10.1146/annurev.bi.60.070191.003545
[ 2] Gould G.W., Bell G.I.
     "Facilitative glucose transporters: an expanding family."
     Trends Biochem. Sci. 15:18-23(1990).
     PubMed=2180146
[ 3] Baldwin S.A.
     "Mammalian passive glucose transporters: members of an ubiquitous
     family of active and passive transport proteins."
     Biochim. Biophys. Acta 1154:17-49(1993).
     PubMed=8507645
[ 4] Maiden M.C.J., Davis E.O., Baldwin S.A., Moore D.C.M., Henderson P.J.F.
     "Mammalian and bacterial sugar transport proteins are homologous."
     Nature 325:641-643(1987).
     PubMed=3543693; DOI=10.1038/325641a0
[ 5] Henderson P.J.F.
     Curr. Opin. Struct. Biol. 1:590-601(1991).
[ 6] Culham D.E., Lasby B., Marangoni A.G., Milner J.L., Steer B.A.,
     van Nues R.W., Wood J.M.
     "Isolation and sequencing of Escherichia coli gene proP reveals
     unusual structural features of the osmoregulatory proline/betaine
     transporter, ProP."
     J. Mol. Biol. 229:268-276(1993).
     PubMed=8421314

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