LARGE catalytic domain has closest homology to GT8 glycosyltransferase involved in lipooligosaccharide synthesis.
The catalytic domain of LARGE is a putative glycosyltransferase. Mutations of LARGE in mouse and human cause dystroglycanopathies, a disease associated with hypoglycosylation of the membrane protein alpha-dystroglycan (alpha-DG) and consequent loss of extracellular ligand binding. LARGE needs to both physically interact with alpha-dystroglycan and function as a glycosyltransferase in order to stimulate alpha-dystroglycan hyperglycosylation. LARGE localizes to the Golgi apparatus and contains three conserved DxD motifs. While two of the motifs are indispensible for glycosylation function, one is important for localization of th eenzyme. LARGE was originally named because it covers approximately large trunck of genomic DNA, more than 600bp long. The predicted protein structure contains an N-terminal cytoplasmic domain, a transmembrane region, a coiled-coil motif, and two putative catalytic domains. This catalytic domain has closest homology to GT8 glycosyltransferase involved in lipooligosaccharide synthesis.