The enzyme encoded by this gene catalyzes the activation of Neu5Ac to Cytidine 5-prime-monophosphate N-acetylneuraminic acid (CMP-Neu5Ac), which provides the substrate required for the addition of sialic acid.Sialic acids of cell surface glycoproteins and glycolipids play a pivotal role in the structure and function of animal tissues.The pattern of cell surface sialylation is highly regulated during embryonic development, and changes with stages of differentiation.Studies of a similar murine protein suggest that this protein localizes to the nucleus.[provided by RefSeq]