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Amyloidogenic glycoprotein (A4 protein or APP) is an integral, glycosylated
membrane brain protein [1,2]. APP is associated with Alzheimer's disease (AD).
This responsibility stems from the fact that a small peptide (of 43 residues),
called the amyloid β protein, which is part of the sequence of A4, is the
major constituent of amyloid deposits in AD and in Down's syndrome. As shown
in the schematic representation below, the amyloid β protein both precedes
and forms part of the unique transmembrane region of A4.
'X': Transmembrane region.
'B': Position of the amyloid beta protein in A4.
The exact function of A4 protein is not yet known, but it has been suggested
that it mediates cell-cell interactions. The sequence of A4 from mammalian
species is well conserved and is also similar to that of other proteins:
Mammalian protein APLP2 (APPH) (YWK-II) (CDEI-binding protein) .
We have derived two patterns specific to these proteins, the first one is a
perfectly conserved octapeptide located in the beginning of the extracellular
domain; the second is a conserved octapeptide located at the C-terminal end of
the cytoplasmic domain.
December 2004 / Pattern and text revised.
PROSITE methods (with tools and information) covered by this documentation:
Dyrks T., Weidemann A., Multhaup G., Salbaum J.M., Lemaire H.-G., Kang J., Muller-Hill B., Masters C.L., Beyreuther K.
Identification, transmembrane orientation and biogenesis of the amyloid A4 precursor of Alzheimer's disease.
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