The X8 domain [2] domain contains at least 6 conserved cysteine residues that presumably form three disulphide bridges. The domain is found in an Olive pollen allergen [1] as well as at the C-terminus of several families of glycosyl hydrolases [2]. This domain may be involved in carbohydrate binding. This domain is characteristic of GPI-anchored domains [4,5].

1: A major allergen from pollen defines a novel family of plant proteins and shows intra- and interspecies cross-reactivity. Barral P, Batanero E, Palomares O, Quiralte J, Villalba M, Rodriguez R; J Immunol 2004;172:3644-3651. PMID:15004167

2: Glycoside hydrolases and glycosyltransferases. Families, modules, and implications for genomics. Henrissat B, Davies GJ; Plant Physiol 2000;124:1515-1519. PMID:11115868

3: A census of carbohydrate-active enzymes in the genome of Arabidopsis thaliana. Henrissat B, Coutinho PM, Davies GJ; Plant Mol Biol 2001;47:55-72. PMID:11554480

4: Identification of the catalytic residues of the first family of beta(1-3)glucanosyltransferases identified in fungi. Mouyna I, Monod M, Fontaine T, Henrissat B, Lechenne B, Latge JP; Biochem J. 2000;347:741-747. PMID:10769178

5: Proteome analysis of Aspergillus fumigatus identifies glycosylphosphatidylinositol-anchored proteins associated to the cell wall biosynthesis. Bruneau JM, Magnin T, Tagat E, Legrand R, Bernard M, Diaquin M, Fudali C, Latge JP; Electrophoresis. 2001;22:2812-2823. PMID:11545413