Abstract
Ten novel α-gliadin genes (Gli-ta, Gli-turg1,
Gli-turg2, Gli-turg3, Gli-turg4, Gli-turg5, Gli-turg6, Gli-cs1, Gli-cs2,
and Gli-cs3) with unique characteristics were isolated from wheat
(Triticum aestivumL.), among which Gli-cs1, Gli-cs2, Gli-cs3, and
Gli-turg6 were pseudogenes. Gli-cs3 and nine other sequences were much
larger and smaller, respectively, than the typical α-gliadins. This
variation was caused by insertion or deletion of the unique domain I and
a polyglutamine region, possibly the result of illegitimate
recombination. Consequently, Gli-cs3 contained 10 cysteine residues,
whereas there were 2 cysteine residues only in the other nine sequences.
Gli-ta/Gli-ta-like α-gliadin genes are normally expressed during the
development of seeds. SDS-PAGE analysis showed that in-vitro-expressed
Gli-ta could form intermolecular disulphide bonds and could be chain
extenders. A protein band similar in size to Gli-ta has been observed in
seed extracts, and mass spectrometry results confirm that the band
contains small molecular mass α-gliadins, which is a characteristic of
the novel α-gliadins. Mass spectrometry results also indicated that the
two cysteine residues of Gli-ta/Gli-ta-like proteins participated in the
formation of intermolecular disulphide bonds in vivo.
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