glycosylphosphatidylinositol-glucanosyltransferase. Group of fungal GH16 members related to Saccharomyces cerevisiae Crh1p. Chr1p and Crh2p are transglycosylases that are required for the linkage of chitin to beta(1-3)glucose branches of beta(1-6)glucan, an important step in the assembly of new cell wall. Both have been shown to be glycosylphosphatidylinositol (GPI)-anchored. A third homologous protein, Crr1p, functions in the formation of the spore wall. They belongs to the family 16 of glycosyl hydrolases that includes lichenase, xyloglucan endotransglycosylase (XET), beta-agarase, kappa-carrageenase, endo-beta-1,3-glucanase, endo-beta-1,3-1,4-glucanase, and endo-beta-galactosidase, all of which have a conserved jelly roll fold with a deep active site channel harboring the catalytic residues.

Xyloglucan endo-transglycosylase (XET) C-terminus. This family represents the C-terminus (approximately 60 residues) of plant xyloglucan endo-transglycosylase (XET). Xyloglucan is the predominant hemicellulose in the cell walls of most dicotyledons. With cellulose, it forms a network that strengthens the cell wall. XET catalyzes the splitting of xyloglucan chains and the linking of the newly generated reducing end to the non-reducing end of another xyloglucan chain, thereby loosening the cell wall. Note that all family members contain the pfam00722 domain.

Glycosyl hydrolases family 16.

Probable xyloglucan endotransglucosylase/hydrolase protein; Provisional

Xyloglucan endotransglycosylase, member of glycosyl hydrolase family 16. Xyloglucan endotransglycosylases (XETs) cleave and religate xyloglucan polymers in plant cell walls via a transglycosylation mechanism. Xyloglucan is a soluble hemicellulose with a backbone of beta-1,4-linked glucose units, partially substituted with alpha-1,6-linked xylopyranose branches. It binds noncovalently to cellulose, cross-linking the adjacent cellulose microfibrils, giving it a key structural role as a matrix polymer. Therefore, XET plays an important role in all plant processes that require cell wall remodeling.