APC10-like DOC1 domain of HECTD3, a HECT E3 ubiquitin ligase protein that mediates substrate ubiquitination. This model represents the APC10/DOC1 domain present in HECTD3, a HECT (Homologous to the E6-AP Carboxyl Terminus) E3 ubiquitin ligase protein. HECT E3 ubiquitin ligases mediate substrate ubiquitination (or ubiquitylation), and are a component of the ubiquitin-26S proteasome pathway for selective proteolytic degradation. They also regulate the trafficking of many receptors, channels, transporters and viral proteins. HECTD3 (HECT domain-containing protein3) contains a C-terminal HECT domain with the active site for ubiquitin transfer onto substrates, and an N-terminal APC10/DOC1 domain, which is responsible for substrate recognition and binding. HECTD3 specifically recognizes the Trio-binding protein, Tara (Trio-associated repeat on actin), implicated in regulating actin cytoskeletal, cell motility and cell growth. Tara also binds to TRF1 and may participate in telomere maintenance and/or mitotic regulation through interacting with TRF1. HECTD3 interacts with and promotes the ubiquitination of Syntaxin 8, an endosomal syntaxin proposed to mediate distinct steps of endosomal protein trafficking. HECTD3-mediated Syntaxin 8 degradation has been suggested to contribute to the pathophysiology of neurodegenerative diseases.

Alpha-L-fucosidase. O-Glycosyl hydrolases (EC 3.2.1.-) are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glycosyl hydrolases, based on sequence similarity, has led to the definition of 85 different families. This classification is available on the CAZy (CArbohydrate-Active EnZymes) web site. Because the fold of proteins is better conserved than their sequences, some of the families can be grouped in 'clans'. Family 29 encompasses alpha-L-fucosidases, which is a lysosomal enzyme responsible for hydrolyzing the alpha-1,6-linked fucose joined to the reducing-end N-acetylglucosamine of the carbohydrate moieties of glycoproteins. Deficiency of alpha-L-fucosidase results in the lysosomal storage disease fucosidosis.

Alpha-L-fucosidase.

Alpha-L-fucosidase [Carbohydrate transport and metabolism]