The X8 domain, which may be involved in carbohydrate binding, is found in an Olive pollen antigen as well as at the C terminus of family 17 glycosyl hydrolases. It contains 6 conserved cysteine residues which presumably form three disulfide bridges.
The X8 domain [ (PUBMED:11115868) ] contains 6 conserved cysteine residues that presumably form three disulphide bridges. The domain is found in an Olive pollen allergen [ (PUBMED:15004167) ] as well as at the C terminus of family 17 glycosyl hydrolases [ (PUBMED:11554480) ]. This domain may be involved in carbohydrate binding.
Family alignment:
There are 8425 X8 domains in 8213 proteins in SMART's nrdb database.
Click on the following links for more information.
Evolution (species in which this domain is found)
Taxonomic distribution of proteins containing X8 domain.
This tree includes only several representative species. The complete taxonomic breakdown of all proteins with X8 domain is also avaliable.
Click on the protein counts, or double click on taxonomic names to display all proteins containing X8 domain in the selected taxonomic class.
Literature (relevant references for this domain)
Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.
A major allergen from pollen defines a novel family of plant proteins and shows intra- and interspecies [correction of interspecie] cross-reactivity.
J Immunol. 2004; 172: 3644-51
Display abstract
Olive tree (Olea europaea) pollen is a main cause of allergy associated with extensive areas of Europe and North America. Ole e 10, a small (10.8 kDa) and acidic (pI 5.8) protein, has been identified as a major allergen from the olive pollen, isolated, and characterized. Circular dichroism analysis gave 17% alpha helix, 33% beta sheet, and 21% beta turn for its secondary structure. Based on amino acid sequences of tryptic peptides, the protein was cloned and sequenced. The allergen consists of a single polypeptide chain of 102 aa, with a signal peptide of 21 residues. Ole e 10 showed homology with the C-terminal domain of another olive allergen, Ole e 9 (1,3-beta-glucanase, 53% identity), with deduced sequences from Arabidopsis thaliana genes (42-46% identity) and with polypeptide segments (Cys boxes) of proteins involved in yeast development (Epd1/Gas-1p/Phr2 families; 42-43% similarity). Ole e 10 showed 55% prevalence for olive-allergic patients and exhibited an IgE response dependent on its conformation. Remarkable IgE cross-reactivity was detected with Ole e 9, but no correlation was observed between the individual IgE responses to both allergens. Ole e 10 shares IgE B cell epitopes with proteins from Oleaceae, Gramineae, Betulaceae, Chenopodiaceae, Cupressaceae, Ambrosia, and Parietaria pollens, latex, and vegetable foods, such as tomato, kiwi, potato, and peach. These data indicate that Ole e 10 is a new pan-allergenic plant protein that shows notable intra- and interspecie IgE cross-reactivity and is a powerful candidate to be involved in pollen-latex-fruit syndrome.
A census of carbohydrate-active enzymes in the genome of Arabidopsis thaliana.
Plant Mol Biol. 2001; 47: 55-72
Display abstract
The synthesis, modification, and breakdown of carbohydrates is one of the most fundamentally important reactions in nature. The structural and functional diversity of glycosides is mirrored by a vast array of enzymes involved in their synthesis (glycosyltransferases), modification (carbohydrate esterases) and breakdown (glycoside hydrolases and polysaccharide lyases). The importance of these processes is reflected in the dedication of 1-2% of an organism's genes to glycoside hydrolases and glycosyltransferases alone. In plants, these processes are of particular importance for cell-wall synthesis and expansion. starch metabolism, defence against pathogens, symbiosis and signalling. Here we present an analysis of over 730 open reading frames representing the two main classes of carbohydrate-active enzymes, glycoside hydrolases and glycosyltransferases, in the genome of Arabidopsis thaliana. The vast importance of these enzymes in cell-wall formation and degradation is revealed along with the unexpected dominance of pectin degradation in Arabidopsis, with at least 170 open-reading frames dedicated solely to this task.
