Figure 1. . The biosynthesis of sialic acid (Neu5Ac) is an intracellular process with enzymes shown in yellow.

Figure 1.

The biosynthesis of sialic acid (Neu5Ac) is an intracellular process with enzymes shown in yellow. The initial steps of this pathway occur in the cytoplasm with the substrate, UDP-GlcNAc, which derives from glucose. In the rate-limiting step of the pathway, UDP-GlcNAc 2-epimerase (encoded by the epimerase domain of GNE) catalyzes the conversion of UDP-GlcNAc into ManNAc. Subsequently, ManNAc kinase (encoded by the kinase domain of GNE) or other kinase enzymes in the cytoplasm phosphorylate ManNAc to ManNAc-6-phosphate. In the cell nucleus, Neu5Ac becomes "activated" to CMP-sialic acid, which is transported to the Golgi, where it donates Neu5Ac in the sialylation of nascent glycoproteins. Mature sialylated glycoproteins can be secreted or become integral plasma membrane proteins (pictured).

Carrillo et al [2018]. Republished with permission.

From: GNE Myopathy

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