Addition of N-acetyl-D-glucosamine to Dolichyl phosphate

In the first step of N glycan precursor (LLO) synthesis, N acetylglucosamine is added, via an alpha 1,3 linkage, to a molecule of dolichyl phosphate, producing N acetyl D glucosaminyl diphosphodolichol (Eckert et al. 1998). This reaction is catalyzed by DPAGT1 (ALG7 in yeast), mutations in which are associated with CDG disorder type I J (Wu et al. 2003) and with congenital myasthenic syndrome with tubular aggregates type 2 (Belaya et al. 2012). The dolichyl phosphate acts as an anchor for the LLO, so that subsequent sugar addition reactions take place on a sugar anchored in the ER membrane.

在N-糖甘露糖前体（LLO）合成的第一步中，通过α1,3键合作用，将N-乙酰葡萄糖胺添加至多聚磷脂分子中，生成N-乙酰-D-甘露氨酰二磷酸多聚磷脂醇（Eckert等，1998年）。此反应由DPAGT1（酵母中的ALG7）催化，该酶的突变与I型CDG疾病（Wu等，2003年）以及伴有管状聚集体先天性肌无力综合征2型（Belaya等，2012年）相关。多聚磷脂醇充当LLO的锚定基，使得后续的糖添加反应在位于内质网膜上的糖锚定基上发生。