ALG8 (enzyme class)

ALG8, also known as alpha-1,3-glucosyltransferase, is a glycosyltransferase enzyme involved in the N-glycosylation pathway. Specifically, ALG8 catalyzes the transfer of a glucose residue from dolichyl-phosphate-glucose to the GlcNAc2Man5GlcNAc2-PP-Dolichol oligosaccharide precursor. This step is essential for the proper assembly of the N-glycan structure, which is subsequently transferred to nascent proteins in the endoplasmic reticulum.

The enzyme is localized to the endoplasmic reticulum membrane. ALG8 mutations in various organisms, including humans, have been linked to congenital disorders of glycosylation (CDG), specifically CDG-I type variants. These deficiencies result in abnormal N-glycosylation, affecting the folding, stability, and function of various glycoproteins. Consequently, individuals with ALG8-related CDG may exhibit a range of symptoms affecting multiple organ systems.

The activity of ALG8 is critical for the correct synthesis and processing of N-linked glycans, impacting protein function and overall cellular homeostasis.