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The immunodominant human allergen of soybean seeds is
a cysteine protease family member called P34 or Gly m Bd
30K. P34 is accumulated at high levels in maturing seeds and
in small quantities in vegetative tissues, where it may have a
pathogen-resistance role. Among cysteine proteases, P34 is
unique in possessing a glycine substitution for an otherwise
invariant cysteine in the active site. Among soybean sensitive
people, P34 accounts for a large majority of IgE crossreactivity.
Soybean sensitivity is also widespread among
farmed animals ranging from pigs to salmon. Human IgE
binding epitopes have been mapped, and the allergenic
epitopes consist of fourteen distinct sites.
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Figure.
Immunogold assay of
Gly m Bd 30 K cross-reactive
proteins in silenced (A) and control (B)
lines. A, Abundant Gly m Bd
30K label in a late maturation
soybean cell of a control. B,
Similar transgenic soybean cell in
which Gly m Bd 30 K accumulation was
suppressed. OB, Oil bodies; PSV, protein storage vacuoles. |