May play an important role in the regulation of sialic acid metabolism. an N-acylneuraminate + CTP = a CMP-N-acyl-beta-neuraminate + diphosphate Mg(2+). Other divalent cations are less effective. Inhibited by CMP-N-acylneuraminate. Amino-sugar metabolism; N-acetylneuraminate metabolism. Homodimer. Liver. Thiol residues may be essential for catalytic activity. Was originally (PubMed:1577759) thought to be the main N-acylneuraminate cytidylyltransferase enzyme in rat. However, it does not correspond to the CMAS protein, which was then been shown to correspond to the major N-acylneuraminate cytidylyltransferase enzyme. The relevance and existence of this sequence is therefore unsure.