ST3GAL5 transfers NeuNAc to ceramides

Following its biosynthesis, a fraction of GalCer reaches the lumen of the Golgi and is reacted with cytidine-5′-monophospho-N-acetylneuraminic acid by the action of the sialyltransferase ST3GAL5 to form N-acetylneuraminyl-GalCer (GM4; sialyl-GalCer) (Shanker and Pieringer, 1983; Ishii et al., 1998; reviewed by Liu & Li, 2013). ST3GAL5 also catalyzes the sialylation of lactosylceramide (LacCer) to ganglioside GM3 and the sialylation of gangliosides GA1/GA2 to gangliosides GM1/GM2. The process is localized in the Golgi membrane (Allende et al., 2000; Stern et al., 2000; Berselli et al., 2006). Deficiencies in ST3GAL5 are the cause of "Salt and Pepper" developmental regression syndrome (SPDRS, MIM:609056; Aoki et al., 2019; reviewed by Inamori & Inokuchi, 2022).

在其生物合成之后，一部分半乳糖Cer进入高尔基体腔室，并在唾液酰基转移酶ST3GAL5的作用下与胞苷-5'-单磷酸-N-乙酰神经氨酸酸发生反应，形成N-乙酰神经氨酸基半乳糖Cer（GM4；唾液酰化半乳糖Cer）（Shanker和Pieringer，1983；Ishii等人，1998；由Liu与Li，2013年综述）。ST3GAL5还催化乳糖Cer的唾液化作用，生成神经节苷脂GM3，以及神经节苷脂GA1/GA2的唾液化作用，生成神经节苷脂GM1/GM2。此过程定位于高尔基体膜上（Allende等人，2000；Stern等人，2000；Berselli等人，2006）。ST3GAL5的缺陷是“盐和胡椒”发育退化综合征（SPDRS，MIM:609056；Aoki等人，2019；由Inamori与Inokuchi，2022年综述）的病因。