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PubMed2006

Glutamine-binding protein from Escherichia coli specifically binds a wheat gliadin peptide. 2. Resonance energy transfer studies suggest a new sensing approach for an easy detection of wheat gliadin.

In this work is presented the first attempt to develop a fluorescence assay for detection of traces of gluten in food by utilizing the recombinant glutamine-binding protein (GlnBP) from E. coli. We found that GlnBP specifically binds the sequence of amino acids present both in gliadin and other prolamines classified as toxic for celiac patients. Affinity chromatography experiments together with mass spectrometry experiments demonstrated that GlnBP can bind the following amino acid sequence XXQPQPQQQQQQQQQQQQL. Sequence alignment experiments pointed out that this sequence is exclusively representative of the gliadin and the other prolamines considered toxic for celiac patients. These findings suggest the development of a competitive resonance energy transfer (RET) assay for an easy and rapid detection of this sequence in raw and cooked food.

Amino Acid Sequence↗

PubMed1979

[A new concept in the surgery of chronic pancreatitis (author's transl)].

There is an obvious advantage to partial duodenopancreatectomy with occlusion of the pancreatic duct by prolamine (a rapidly solidifying aminoacid solution) for the prevention of recurrences, while preserving the stomach and proximal duodenum, in the treatment of severe destruction of the pancreas, localised to the head or generalised. The death rate of partial duodenopancreactectomy has been lowered from 8.5 to 2.3% since using this method. Compared with total duodenopancreatectomy which--according to the authors' earlier results carried a postoperative mortality of 20%--the operative risk has been reduced to a tenth. Taking into account the benign nature of chronic pancreatitis, on the other hand, and the extent of the operative operation, on the other, the present death-rate of 2.3% would appear reasonable. Occlusion of the pancreatic duct with prolamine in order to exclude any still present excretory pancreatic function in the residual pancreatic tissue has made all patients pain-free. No early recurrence has been observed.

Amino Acids↗

PubMed2002

The use of extended amino acid motifs for focussing on toxic peptides in coeliac disease.

Cereal prolamins of wheat, rye and barley are the major proteins that have been implicated in toxicity in patients with coeliac disease. The gliadins of wheat are the best characterised with the identification of toxic peptides from rye and barley not as well advanced. This study has employed extended motifs, based on the known toxic motifs are derived from the sequence of A-gliadin, to search protein databases for matches with coeliac-toxic cereals. The results obtained have provided pointers to specific regions in rye and barley prolamins, which have received little attention in in vitro and in vivo studies of toxicity in coeliac disease. The results obtained in this study indicate that the size of the extended motif is critical when searching for coeliac-toxic cereals using protein databases. Extended motifs that are common to all three coeliac-toxic cereals and found in active wheat gliadin peptides are QQPYP, PQQPY and QQQPFP.

Amino Acid Sequence↗

PubMed1998

Identification of polypeptides associated with an enriched cytoskeleton-protein body fraction from developing rice endosperm.

Recent evidence has shown that the prolamine polysomes are attached not only to the endoplasmic reticulum membranes that bound the prolamine protein bodies (PBs) but also to cytoskeleton elements associated with this subcellular fraction. To learn more about the nature of the proteins that are associated with this supra-macromolecular complex, proteins extracted from an enriched cytoskeleton-PB fraction were resolved by two-dimensional polyacrylamide gel electrophoresis under non-equilibrium conditions and analyzed for their composition by immunological and biochemical methods. Immunoblot analysis indicated the presence of the cytoskeletal proteins, actin and tubulin, and the cytoskeletal-associated protein EF1 alpha in this fraction. Microsequencing of selected polypeptides revealed a diversity of protein sequences. In addition to contaminating storage proteins which are selectively solubilized by the isolation procedure, several ribosomal proteins and histone H3 were also identified. Some of the remaining polypeptides showed partial homology to protein sequences deposited in the database, several of which are cytoskeleton-associated proteins.

Amino Acid Sequence↗

PubMed1987

Subtotal resection of the head of the pancreas combined with ductal obliteration of the distal pancreas in chronic pancreatitis.

Subtotal resection of the head of the pancreas combined with duct obliteration of the distal pancreas by prolamine was performed in 12 selected patients who had chronic alcohol-induced pancreatitis with most destruction in the proximal pancreas. The main indication for operation was intractable pain. There was no postoperative mortality but morbidity was high when no pancreaticojejunostomy was constructed. After a follow-up period of 32 months, lasting pain relief was obtained in 10 patients; pseudocyst formation occurred in three patients; calcification of the distal pancreas, absent before operation, was demonstrated in four of six patients; six of 11 nondiabetic patients became hyperglycemic either abruptly (1 patient) or progressively (5 patients); quality of life improved in most patients. This procedure preserves the stomach, duodenum, spleen, distal pancreas and common bile duct if possible. However, pancreatic ductal obliteration with prolamine does not prevent relapses of chronic pancreatitis.

Adult↗

PubMed1984

The effect of duct obliteration on the histology and endocrine function of the canine pancreas.

Although duct obliteration is a safe and effective method for ablation of exocrine secretion in segmental pancreas transplantation, it remains to be clarified whether its effects are restricted to the exocrine tissue. In 20 dogs (beagles 9-15 kg) the right lobe of the pancreas was removed and the ductal system of the left lobe was injected with the duct-obliterants neoprene (6 dogs), polyisoprene (6 dogs), or prolamine (8 dogs). In this study, i.v. glucose tolerance tests (the results of which are expressed in K values) and relaparotomies for taking biopsies were performed at 1, 3, and 12 months after duct obliteration. Biopsies were studied histologically and immunohistochemically in a qualitative and semiquantitative fashion. Three prolamine-injected dogs developed diabetes. All other dogs maintained normal fasting blood glucose levels but showed reduced K values at 1 month after duct obliteration. Further deterioration of glucose tolerance was not observed up to 12 months. Differences in K values depending on the type of obliterant were insignificant at all intervals. The exocrine tissue was completely replaced by fibrosis at 3 months after duct obliteration, and the architecture of the islets was disrupted. Morphometrical analysis of relative numbers of different endocrine cell types showed transient changes at 1 month after duct obliteration, but did not differ from unmodified controls at 12 months. We conclude that the effects of duct obliteration are not restricted to the exocrine pancreatic tissue, but that the endocrine pancreas is interfered with as well. Changes in islet function and histology are brought about during the first month after duct obliteration and stabilize thereafter.

Animals↗

PubMed2001

Genomics analysis of genes expressed in maize endosperm identifies novel seed proteins and clarifies patterns of zein gene expression.

We analyzed cDNA libraries from developing endosperm of the B73 maize inbred line to evaluate the expression of storage protein genes. This study showed that zeins are by far the most highly expressed genes in the endosperm, but we found an inverse relationship between the number of zein genes and the relative amount of specific mRNAs. Although alpha-zeins are encoded by large multigene families, only a few of these genes are transcribed at high or detectable levels. In contrast, relatively small gene families encode the gamma- and delta-zeins, and members of these gene families, especially the gamma-zeins, are highly expressed. Knowledge of expressed storage protein genes allowed the development of DNA and antibody probes that distinguish between closely related gene family members. Using in situ hybridization, we found differences in the temporal and spatial expression of the alpha-, gamma-, and delta-zein gene families, which provides evidence that gamma-zeins are synthesized throughout the endosperm before alpha- and delta-zeins. This observation is consistent with earlier studies that suggested that gamma-zeins play an important role in prolamin protein body assembly. Analysis of endosperm cDNAs also revealed several previously unidentified proteins, including a 50-kD gamma-zein, an 18-kD alpha-globulin, and a legumin-related protein. Immunolocalization of the 50-kD gamma-zein showed this protein to be located at the surface of prolamin-containing protein bodies, similar to other gamma-zeins. The 18-kD alpha-globulin, however, is deposited in novel, vacuole-like organelles that were not described previously in maize endosperm.

Amino Acid Sequence↗

PubMed2006

Retention of a bean phaseolin/maize gamma-Zein fusion in the endoplasmic reticulum depends on disulfide bond formation.

Most seed storage proteins of the prolamin class accumulate in the endoplasmic reticulum (ER) as large insoluble polymers termed protein bodies (PBs), through mechanisms that are still poorly understood. We previously showed that a fusion between the Phaseolus vulgaris vacuolar storage protein phaseolin and the N-terminal half of the Zea mays prolamin gamma-zein forms ER-located PBs. Zeolin has 6 Cys residues and, like gamma-zein with 15 residues, is insoluble unless reduced. The contribution of disulfide bonds to zeolin destiny was determined by studying in vivo the effects of 2-mercaptoethanol (2-ME) and by zeolin mutagenesis. We show that in tobacco (Nicotiana tabacum) protoplasts, 2-ME enhances interactions of newly synthesized proteins with the ER chaperone BiP and inhibits the secretory traffic of soluble proteins with or without disulfide bonds. In spite of this general inhibition, 2-ME enhances the solubility of zeolin and relieves its retention in the ER, resulting in increased zeolin traffic. Consistently, mutated zeolin unable to form disulfide bonds is soluble and efficiently enters the secretory traffic without 2-ME treatment. We conclude that disulfide bonds that lead to insolubilization are a determinant for PB-mediated protein accumulation in the ER.

Base Sequence↗

PubMed1985

Does the reticulin binding property of cereal proteins demonstrable in vitro have pathogenetic significance for coeliac disease?

We used an indirect immunofluorescence technique, using rabbit antisera against cereal protein extracts, to determine which cereal proteins bind to reticulin in tissue sections and which do not. Wheat albumin extracts and globulins and gliadin extracts from a range of different wheat varieties, and prolamine extracts of barley and rye each bound to reticulin in vitro, while prolamine extracts of maize and rice did not. Wheat gluten subfractions were also tested. Subfractions B and C and subfractions B2 and B3 did bind, but fraction A and subfraction B1 did not. The results suggest an association between in vitro reticulin binding and the ability to induce gluten sensitive enteropathy on feeding.

Animals↗

PubMed1992

Gliadin induced changes in the expression of MHC-class II antigens by human small intestinal epithelium. Organ culture studies with coeliac disease mucosa.

Jejunal biopsies from 16 treated coeliac disease patients and from nine controls were cultured with and without a peptic-tryptic digest of gliadin. Cultures with a peptic-tryptic digest of maize prolamins were also undertaken. Frozen sections of baseline and cultured mucosa were stained by immunofluorescence with an anti-HLA-DR monoclonal antibody. Before culture the villous epithelium from both controls and treated coeliac disease expressed DR molecules while the crypt epithelium did not. When biopsies from treated coeliac disease were cultured with gliadin the expression of DR was enhanced in the crypt epithelium in eight of 14 cultures and in 11 of 14 was reduced or absent on the villous epithelium. No change was observed in control cultures. We conclude that gliadin is capable of inducing HLA-DR on the crypt epithelium of in vitro cultured coeliac disease mucosa, providing indirect evidence that gliadin may activate cell mediated immune mechanisms within the small bowel mucosa. This model could prove useful in identifying the immunogenic sequence(s) of gliadins and related prolamins.

Celiac Disease↗

PubMed2003

Structural organization of the barley D-hordein locus in comparison with its orthologous regions of wheat genomes.

D hordein, a prolamin storage protein of barley endosperms, is highly homologous to the high molecular weight (HWM) glutenin subunits, which are the major determinants of bread-making quality in wheat flour. In hexaploid wheat (AABBDD), each genome contains two paralogous copies of HMW-glutenin genes that encode the x- and y-type HMW-glutenin subunits. Previously, we reported the sequence analysis of a 102-kb genomic region that contains the HMW-glutenin locus of the D genome from Aegilops tauschii, the donor of the D genome of hexaploid wheat. Here, we present the sequence analysis of a 120-kb D-hordein region of the barley genome, a more distantly related member of the Triticeae grass tribe. Comparative sequence analysis revealed that gene content and order are generally conserved. Genes included in both of these orthologous regions are arranged in the following order: a Xa21-like receptor kinase, an endosperm globulin, an HMW prolamin, and a serine (threonine) protein kinase. However, in the wheat D genome, a region containing both the globulin and HMW-glutenin gene was duplicated, indicating that this duplication event occurred after the separation of the wheat and barley genomes. The intergenic regions are divergent with regard to the sequence and structural organization. It was found that different types of retroelements are responsible for the intergenic structure divergence in the wheat and barley genomes. In the barley region, we identified 16 long terminal repeat (LTR) retrotransposons in three distinct nested clusters. These retroelements account for 63% of the contig sequence. In addition, barley D hordein was compared with wheat HMW glutenins in terms of cysteine residue conservation and repeat domain organization.

Amino Acid Sequence↗

PubMed1993

Variability among members of the Hor-2 multigene family.

The hordeins comprise the major prolamin storage proteins of barley. Two major and one minor gene families encode these alcohol-soluble proteins. The Hor-2 gene family encoding the B-hordeins has been estimated to contain 15-30 copies. Although several genes encoding B-hordeins have been cloned and sequenced, little is known about the mechanisms responsible for the generation of the enormous genetic variability at this locus. Polymerase chain reaction sequence amplification provided a simple technique that permitted the amplification of the Hor-2 gene family members from the genomes of several barley genotypes. Sequence analysis of clones permitted the identification of a region within the Hor-2 structural gene that appears to undergo recombinational and slippage-like gene conversion events. In this report we describe variability of the B-hordein genes, possible mechanisms responsible for it, and implications this may have on the evolution of prolamin-encoding gene families.

Base Sequence↗

PubMed2006

Study of IgE antigenic relationships in hypersensitivity to hydrolyzed wheat proteins and wheat-dependent exercise-induced anaphylaxis.

BACKGROUND: Wheat is involved in different forms of respiratory, food and contact allergy. The IgE of patients generally reacts with various flour proteins. It is not known if antigenic relationships could explain some of these reactions and if proteins could be involved in different pathologies. METHODS: Two sera were selected as representative of patients with either wheat-dependent exercise-induced anaphylaxis (WDEIA) or hypersensitivity to hydrolyzed wheat proteins (HHWP). Their IgE specificity was studied with wheat, barley and rye proteins, using immunoblot, and immunoblot inhibition with recombinant gamma-3 hordein. This protein was chosen for its cross-reactivity with omega-5 gliadin, a major allergen in WDEIA. RESULTS: The IgE from both sera strongly reacted with natural and recombinant gamma-3 hordein but displayed different patterns of reactivity with wheat, barley and rye proteins. Those from the WDEIA patient showed expected reactions with omega-5 gliadin, gamma-35 and gamma-75 secalins, but also with wheat low-molecular-weight glutenin subunits (LMW-GS), and not with C hordeins. On the contrary, IgE from a HHWP patient reacted with C hordeins, various omega gliadins, and gamma-75 secalin, but very weakly with gamma-35 secalin and LMW-GS. Recombinant gamma-3 hordein inhibited strongly but not totally the WDEIA patient's IgE binding to prolamins. No such inhibition could be observed for the HHWP patient's IgE. CONCLUSIONS: At least part of the reactions of prolamins with the IgE from the WDEIA patient was due to antigenic homologies. The occurrence of cross-reacting carbohydrates was unlikely. These common IgE epitopes were not involved in the pathology of the HHWP patient.

Adult↗

PubMed1988

Western immunoblotting of cereal proteins with monoclonal antibodies to wheat gliadin to investigate coeliac disease.

Western immunoblotting was used to investigate the binding of two monoclonal antibodies raised against unfractionated wheat gliadin to different cereal protein fractions separated by SDS-PAGE. Our results confirm the presence of considerable epitope sharing between the gliadin subfractions as well as barley and rye prolamins; however, there was less binding of these antibodies to bands present in oat avenins and maize zeins. The pattern of binding of one of these two antibodies to different cereal prolamins as well as to Frazer's fraction III corresponds closely to the known toxicity of these proteins to patients with coeliac disease.

Antibodies, Monoclonal↗

PubMed1995

Antibody response against wheat, rye, barley, oats and corn: comparison between gluten-sensitive patients and monoclonal antigliadin antibodies.

The antibody response of patients with gluten-sensitive enteropathy and dermatitis herpetiformis against alcohol-soluble prolamines of wheat, rye, barley, oats and corn assessed by immunoblotting was compared to the staining patterns produced by monoclonal antigliadin antibodies. Both monoclonal antibodies (MAbs) and patient serum reacted with wheat, rye, barley and oats, the patient serum showing individual variation both in IgA and IgG stainings. A broad reactivity with polypeptides from 30 to 68 kD was, however, typical for patient serum and comparable to the reactivity of two broadly reacting antigliadin MAbs. This kind of broad reactivity of the MAb may suggest that it binds to glutamine-repeating sequences of highly homologous gliadin polypeptides. Glutamine- and proline-containing motifs Pro-Ser-Gln-Gln and Gln-Gln-Gln-Pro are also included in the peptides toxic to the celiac small intestinal mucosa. Our study indicates that the humoral response of the patients may detect similar structures, in oat prolamines as well. Patient serum and one of the MAbs also reacted with a 22-kD polypeptide of corn extract. The meaning of this reactivity is not known, and further characterization of the antigenic epitopes of different cereals will be important.

Amino Acid Sequence↗

PubMed2004

Mass spectrometry in the characterization of cereal seed proteins.

In less then a decade, applications of matrix-assisted laser desorption/ionisation (MALDI) and electrospray ionisation (ESI) mass spectrometry to the investigation of prolamins have rapidly evolved from measurements of the molecular mass of isolated proteins to a proteomic approach attempting to characterise the complete protein pattern in the seed. Mass spectrometry is currently making significant contributions to the understanding of the composition and structure of the gluten proteins and, in turn, to the elucidation of structure-function relationships. Results obtained using mass spectrometry, including determination of the molecular masses of prolamins, direct verification of gene-derived sequences, determination of the number of cysteine residues and localisation of disulphide bonds, investigation of the gluten toxicity for celiac patients, qualitative and quantitative determination of gliadins in food and determination of the protein pattern and its modification during seed maturation by proteomic approaches, are summarised here, to illustrate current trends and individuate possible future perspectives.

Celiac Disease↗

PubMed2007

Protein extraction from cereal seeds.

Seeds may contain different components such as starch and complex carbohydrates that can seriously reduce protein extraction. The proteins in cereal seeds are usually classified in four groups according to their solubility criteria: albumins, globulins, prolamins, and glutelins. They can be specifically extracted. A general procedure for extracting the proteins present in green seeds or immature cereal kernels is given. Then several procedures mostly adapted to cereal seeds are reported for: (1) the whole storage proteins (mostly prolamins and glutelins); (2) the albumins-globulins extracted using salt buffer; (3) the amphiphilic proteins extracted using a phase partitioning process; and (4) the proteins strongly attached to or within the starch granules of the seed endosperm. These procedures have been used for 2-D electrophoresis and proteomic analyses.

Chemical Precipitation↗

PubMed2004

An opaque-2-like transcription factor from pearl millet.

Pearl millet (Pennisetum glaucum L.), a species of the Poaceae family, is an important food crop in Africa, Asia and South America. Its nutritional value is due to storage prolamins accumulated in the seeds. In other species of the same family, the expression of the genes coding for storage prolamins is mediated by the regulatory protein opaque-2. In this paper we show that an opaque-2 -like protein is present in pearl millet too and is expressed during the early stages of seed development. The organization of the gene coding for this protein is similar to that of orthologous genes in other Poaceae species, i.e. six exons separated by five introns. A comparison of amino acid homologies with other described opaque-2 proteins is presented.

Amino Acid Sequence↗