Endo-beta-N-acetylglucosaminidase D [Carbohydrate transport and metabolism].

Endo-beta-N-acetylglucosaminidase (ENGase) hydrolyzes the N-N'-diacetylchitobiosyl core of N-glycosylproteins. The beta-1,4-glycosyl bond located between two N-acetylglucosamine residues is hydrolyzed such that N-acetylglucosamine 1 remains with the protein and N-acetylglucosamine 2 forms the reducing end of the released glycan. ENGase is a key enzyme in the processing of free oligosaccharides in the cytosol of eukaryotes. Oligosaccharides formed in the lumen of the endoplasmic reticulum are transported into the cytosol where they are catabolized by cytosolic ENGases and other enzymes, possibly to maximize the reutilization of the component sugars. ENGases have an eight-stranded alpha/beta barrel topology and are classified as a family 85 glycosyl hydrolase (GH85) domain. The GH85 ENGases are sequence-similar to the family 18 glycosyl hydrolases, also known as GH18 chitinases. An ENGase-like protein is also found in bacteria and is included in this alignment model.

Glycosyl hydrolase family 85. Family of endo-beta-N-acetylglucosaminidases. These enzymes work on a broad spectrum of substrates.

Por secretion system C-terminal sorting domain. Species that include Porphyromonas gingivalis, Fibrobacter succinogenes, Flavobacterium johnsoniae, Cytophaga hutchinsonii, Gramella forsetii, Prevotella intermedia, and Salinibacter ruber average twenty or more copies of a C-terminal domain, represented by this model, associated with sorting to the outer membrane and covalent modification.

Secretion system C-terminal sorting domain. Species that include Porphyromonas gingivalis, Fibrobacter succinogenes, Flavobacterium johnsoniae, Cytophaga hutchinsonii, Gramella forsetii, Prevotella intermedia, and Salinibacter ruber have on average twenty or more copies of this C-terminal domain, associated with sorting to the outer membrane and covalent modification. This domain targets proteins to type IX secretion systems and is secreted then cleaved off by a C-terminal signal peptidease. Based on similarity to other families it is likely that this domain adopts an immunoglobulin like fold.