OTU (ovarian tumor) domain of bifunctional UDP-N-acetylglucosamine transferase and deubiquitinase ALG13 and similar proteins
Bifunctional UDP-N-acetylglucosamine transferase and deubiquitinase ALG13 is alco called asparagine-linked glycosylation 13 homolog, glycosyltransferase 28 domain-containing protein 1 (GLT28D1), or UDP-N-acetylglucosamine transferase subunit ALG13 homolog. It displays both glycosyltransferase (EC 2.4.1.141) and deubiquitinase (DUB)/ubiquitin thioesterase (EC 3.4.19.12) activities. With ALG14, it forms a UDP-N-acetylglucosamine transferase that catalyzes the second step of eukaryotic N-linked glycosylation in the endoplasmic reticulum. ALG13 variants cause a form of early infantile epileptic encephalopathy known as EIEE36 refractory seizures, neurodevelopmental impairment, and poor prognosis; given the essential role of ALG13 in glycosylation, it is also considered a congenital disorder of glycosylation (CDG). This subfamily also contains OTU domain-containing protein 4 (OTUD4), also called HIV-1-induced protein HIN-1, a DUB that specifically deubiquitinates 'Lys-63'-polyubiquitinated MYD88 adapter protein upon phosphorylation, triggering down-regulation of NF-kappa-B-dependent transcription of inflammatory mediators. This subfamily belongs to the OTU family of cysteine proteases that use a conserved cysteine, histidine, and an aspartate, as the catalytic triad.