CMPNeu5Acn

CMPNeu5Acn, more commonly called CMP-Neu5Ac, is the activated cytidine monophosphate form of N-acetylneuraminic acid. It serves as the donor substrate for sialyltransferases, enzymes that attach sialic acid to glycoconjugates on glycoproteins and glycolipids in the secretory pathway.

Biosynthesis begins with the production of N-acetylneuraminic acid (Neu5Ac) in the cytosol via the sialic acid biosynthetic pathway. Neu5Ac is then activated by cytidine monophosphate sialic acid synthetase (CMAS) using CTP to form CMP-Neu5Ac. The activated sugar nucleotide is transported into the Golgi lumen by the CMP-sialic acid transporter (SLC35A1). In the Golgi, sialyltransferases transfer Neu5Ac from CMP-Neu5Ac to terminal positions on N- or O-linked glycans and glycolipids, thereby completing the sialylation step.

Functionally, sialylation mediated by CMP-Neu5Ac influences many aspects of cell biology, including cell–cell and cell–matrix interactions, protein stability, receptor activity, and immune recognition. The availability of CMP-Neu5Ac can regulate the extent and pattern of sialylation, making CMAS activity and CMP-sialic acid transport central to glycan diversity on the cell surface.

Clinical and research notes: Alterations in CMP-Neu5Ac metabolism or its transport can perturb glycan structures and have been investigated in the context of developmental biology and congenital disorders of glycosylation. Genes involved in CMP-Neu5Ac synthesis and transport, such as CMAS and SLC35A1, are studied for their roles in glycosylation and immune function. CMP-Neu5Ac is also widely used in biochemical assays and glycoengineering to modify glycan structures in vitro.