{PDOC00113}
{PS00123; ALKALINE_PHOSPHATASE}
{BEGIN}
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* Alkaline phosphatase active site *
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Alkaline phosphatase (EC 3.1.3.1) (ALP) [1] is a zinc and magnesium-containing
metalloenzyme  which hydrolyzes phosphate esters, optimally at high pH.  It is
found in nearly  all living organisms,  with the exception of some plants.  In
Escherichia coli, ALP (gene phoA) is found in the periplasmic space.  In yeast
it (gene  PHO8)  is  found  in  lysosome-like vacuoles and in mammals, it is a
glycoprotein attached to the membrane by a GPI-anchor.

In mammals, four different isozymes are currently known [2]. Three of them are
tissue-specific:  the  placental,  placental-like (germ cell)   and intestinal
isozymes.  The fourth form is  tissue non-specific and was previously known as
the liver/bone/kidney isozyme.

Streptomyces' species  involved  in  the  synthesis  of  streptomycin (SM), an
antibiotic, express  a  phosphatase (EC 3.1.3.39) (gene strK) which is  highly
related to ALP.   It specifically cleaves  both  streptomycin-6-phosphate and,
more slowly, streptomycin-3"-phosphate.

A serine is involved   in the catalytic activity of ALP. The region around the
active site serine is relatively well conserved and can be used as a signature
pattern.

-Consensus pattern: [IV]-x-D-S-[GAS]-[GASC]-[GAST]-[GA]-T
                    [S is the active site residue]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in SWISS-PROT: 3.
-Last update: June 1994 / Text revised.

[ 1] Trowsdale J., Martin D., Bicknell D., Campbell I.
     Biochem. Soc. Trans. 18:178-180(1990).
[ 2] Manes T., Glade K., Ziomek C.A., Millan J.L.
     Genomics 8:541-554(1990).
[ 3] Mansouri K., Piepersberg W.
     Mol. Gen. Genet. 228:459-469(1991).

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