ALG3（Asparagine-Linked Glycosylation 3）是一种编码α-1,3-甘露糖基转移酶的基因，属于ALG基因家族（Asparagine-Linked Glycosylation家族），该家族成员主要参与N-糖基化途径，负责在蛋白质合成过程中将寡糖链连接到天冬酰胺残基上，这一过程对蛋白质的正确折叠、稳定性和功能至关重要。ALG3在N-糖基化途径的早期阶段发挥作用，催化甘露糖残基添加到脂联寡糖前体（Dol-PP-Man5GlcNAc2）上，形成Dol-PP-Man6GlcNAc2，这是后续糖链延伸的关键步骤。ALG3的突变会导致先天性糖基化障碍（CDG），特别是CDG-Id型，患者表现为严重的神经系统异常、发育迟缓、癫痫、肌张力低下和免疫缺陷等症状，突变的ALG3基因会导致酶活性丧失或降低，从而影响N-糖基化过程，导致糖蛋白功能异常。ALG3过表达的研究较少，但理论上可能干扰正常的糖基化平衡，影响蛋白质折叠和质量控制，甚至可能引发内质网应激反应。相反，ALG3表达降低或功能缺失会导致N-糖基化缺陷，影响多种依赖糖基化的蛋白质，如细胞表面受体、分泌蛋白和溶酶体酶等，进而导致细胞信号传导、免疫应答和代谢紊乱。ALG基因家族的共性在于它们均参与内质网中的N-糖基化途径，各成员在不同步骤中催化特定的糖基转移反应，共同确保糖蛋白的正确合成和修饰。ALG3的生物学功能凸显了N-糖基化在维持细胞稳态和机体健康中的重要性，其突变或表达异常与多种疾病相关，尤其是先天性代谢障碍。

该基因编码的ALG3家族??的一个成员。编码蛋白催化在阿尔法1,3联动Man5GlcNAc2-PP劳工部加入第一DOL-P-人源性甘露糖。该基因缺陷已与特点是不正常的N-糖基化的糖基化类型ID（CDG-ID）的先天性障碍有关。已发现该基因编码不同亚型的多个抄本变形。 [由RefSeq的，2008年11月提供]

ALG3, a member of the asparagine-linked glycosylation gene family, encodes the α-1,3-mannosyltransferase enzyme that operates within the endoplasmic reticulum to facilitate the early stages of N-linked glycosylation. This critical post-translational modification involves the sequential assembly of oligosaccharide chains onto asparagine residues of nascent proteins, a process fundamental to ensuring proper protein folding, structural stability, and functional integrity. Specifically, ALG3 catalyzes the transfer of a mannose residue from a dolichol pyrophosphate-linked pentasaccharide precursor (Dol-PP-Man5GlcNAc2) to form Dol-PP-Man6GlcNAc2, a pivotal step that enables subsequent elongation of the glycan chain. Disruptions in ALG3 function, typically resulting from loss-of-function mutations, are associated with congenital disorder of glycosylation type Id (CDG-Id), a severe metabolic disorder characterized by profound neurological abnormalities, developmental delay, epilepsy, hypotonia, and immunodeficiency. The underlying pathology stems from impaired N-glycosylation, which compromises the function of diverse glycoproteins, including cell surface receptors, secreted proteins, and lysosomal enzymes, thereby disrupting cellular signaling, immune responses, and metabolic homeostasis. While the consequences of ALG3 loss are well-documented, theoretical considerations suggest that its overexpression could potentially perturb glycosylation balance, exacerbate protein quality control issues, and trigger endoplasmic reticulum stress. Collectively, ALG3 exemplifies the essential role of the N-glycosylation pathway in maintaining cellular homeostasis, highlighting how defects in this enzymatic cascade contribute to a spectrum of congenital metabolic diseases.

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