2 research outputs found
Farinin: Characterization of a Novel Wheat Endosperm Protein Belonging to the Prolamin Superfamily
Starch granule surface-associated
proteins were separated by HPLC
and identified by direct protein sequencing. Among the proteins identified
was one that consisted of two polypeptide chains of 11 and 19 kDa
linked by disulfide bonds. Sequencing of tryptic peptides from each
of the polypeptides revealed similarities between some of the peptides
and avenin-like b proteins encoded by partial cDNAs in NCBI. To identify
a contiguous sequence that matched all of the peptides, contigs encoding
three avenin-like b proteins were constructed from ESTs of the cultivar
Butte 86. All peptide sequences were found in a protein encoded by
one of these contigs that had not been identified previously. Protein
and DNA sequences indicated that the two polypeptide chains were derived
from a parent protein that had been cleaved at the C-terminal position
of an asparagine residue. The name farinin is suggested for this protein
and other avenin-like b proteins. Evolutionary relationships of the
protein are discussed and a simple computer molecular model was constructed.
On the basis of its sequence, the new protein was likely to be allergenic
but unlikely to be active in celiac disease
Specific Nongluten Proteins of Wheat Are Novel Target Antigens in Celiac Disease Humoral Response
While
the antigenic specificity and pathogenic relevance of immunologic
reactivity to gluten in celiac disease have been extensively researched,
the immune response to nongluten proteins of wheat has not been characterized.
We aimed to investigate the level and molecular specificity of antibody
response to wheat nongluten proteins in celiac disease. Serum samples
from patients and controls were screened for IgG and IgA antibody
reactivity to a nongluten protein extract from the wheat cultivar <i>Triticum aestivum</i> Butte 86. Antibodies were
further analyzed for reactivity to specific nongluten proteins by
two-dimensional gel electrophoresis and immunoblotting. Immunoreactive
molecules were identified by tandem mass spectrometry. Compared with
healthy controls, patients exhibited significantly higher levels of
antibody reactivity to nongluten proteins. The main immunoreactive
nongluten antibody target proteins were identified as serpins, purinins,
α-amylase/protease inhibitors, globulins, and farinins. Assessment
of reactivity toward purified recombinant proteins further confirmed
the presence of antibody response to specific antigens. The results
demonstrate that, in addition to the well-recognized immune reaction
to gluten, celiac disease is associated with a robust humoral response
directed at a specific subset of the nongluten proteins of wheat