|Gene:||Cmas||Accession Number: G-11088 (MetaCyc)|
Species: Rattus norvegicus
Subunit composition of
cytidine 5'-monophosphate N-acetylneuraminate synthetase = [Cmas]2
cytidine 5'-monophosphate N-acetylneuraminate synthetase subunit = Cmas
The native apparent molecular mass was determined by gel filtration chromatography [RodriguezAparic92].
This enzyme found in eukaryotes and prokaryotes has an important role in activation of sialic acids to their CMP-derivatives for use as a donor in sialyltransferase reactions. Its cloning, characterization, localization and structure have been reviewed [Kean04, MunsterKuhnel04]. In vertebrates this enzyme has been shown to be localized primarily in the nucleus and its amino acid sequence contains a nuclear localization signal and two nuclear export signals. The nuclear export signals are absent in the insect and bacterial enzymes [Fujita07].
In vertebrates it has been cloned from Homo sapiens, Mus musculus and Oncorhynchus mykiss (rainbow trout) although the substrate specificity for different sialic acids varies among species. Cytidine 5'-monophosphate N-acetylneuraminate synthetases are crucial in determining cellular sialylation patterns and are of interest as drug targets (in [Fujita05]). A simple assay for this enzyme has been developed to facilitate high-throughput analysis in rational drug design [Fujita05].
The native enzyme has been purified from rat [RodriguezAparic92] and bovine [Vionnet99] sources. In rat tissues, the enzyme has been detected in brain, kidney, heart, spleen, liver, stomach, intestine, lung, thymus, prostate and urinary bladder. However, it was not found in skeletal muscle [RevillaNuin98].
The subunit structure has been reported to vary among species. The native rat enzyme was determined to be a homodimer [RodriguezAparic92]. The mouse enzyme (see cytidine 5'-monophosphate N-acetylneuraminate synthetase) was proposed to be a homotetramer consisting of two dimers, based on crystal structure analysis of the N-terminal catalytic domain [Krapp03]. However, the functionally active unit for the mouse and bacterial enzyme is the homodimer. Homotetramer formation may explain the oligomerization seen during purification of the enzyme from different species (reviewed in [MunsterKuhnel04]).
The subunit apparent molecular mass was determined by SDS-PAGE [RodriguezAparic92].
Molecular Weight of Polypeptide: 48.129 kD (from nucleotide sequence), 58.0 kD (experimental) [RodriguezAparic92 ]
Molecular Weight of Multimer: 116.0 kD (experimental) [RodriguezAparic92]
|Cellular Component:||GO:0005634 - nucleus [RodriguezAparic92]|
Enzymatic reaction of: cytidine 5'-monophosphate N-acetylneuraminate synthetase
Synonyms: cytidine 5'-monophosphate N-acetylneuraminic acid synthetase, N-acylneuraminate cytidylyltransferase, CMP-N-acetylneuraminic acid synthetase, CMP-NeuNAc synthetase, CMP-sialic acid synthetase, cytidine monophosphate sialic acid synthetase
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
The reaction is favored in the direction shown.
The enzyme required Mg2+ for activity, but it could be replaced by the divalent cations shown. It was highly specific for CTP. It was also inhibited by its product, CMP-N-acetyl-β-neuraminate [RodriguezAparic92].
Inhibitors (Unknown Mechanism): CMP-N-acetyl-β-neuraminate [RodriguezAparic92] , N-ethylmaleimide [RodriguezAparic92] , p-hydroxymercuribenzoate [RodriguezAparic92] , 5,5'-dithio-bis-2-nitrobenzoate [RodriguezAparic92] , Hg2+ [RodriguezAparic92] , Fe2+ [RodriguezAparic92] , ammonium sulfate [RodriguezAparic92] , Cu2+ [RodriguezAparic92] , Zn2+ [RodriguezAparic92]
T(opt): 45 °C [RodriguezAparic92]
pH(opt): 8.0 [RodriguezAparic92]
Fujita05: Fujita A, Sato C, Munster-Kuhnel AK, Gerardy-Schahn R, Kitajima K (2005). "Development of a simple and efficient method for assaying cytidine monophosphate sialic acid synthetase activity using an enzymatic reduced nicotinamide adenine dinucleotide/oxidized nicotinamide adenine dinucleotide converting system." Anal Biochem 337(1);12-21. PMID: 15649371
Fujita07: Fujita A, Sato C, Kitajima K (2007). "Identification of the nuclear export signals that regulate the intracellular localization of the mouse CMP-sialic acid synthetase." Biochem Biophys Res Commun 355(1);174-80. PMID: 17292865
Krapp03: Krapp S, Munster-Kuhnel AK, Kaiser JT, Huber R, Tiralongo J, Gerardy-Schahn R, Jacob U (2003). "The crystal structure of murine CMP-5-N-acetylneuraminic acid synthetase." J Mol Biol 334(4);625-37. PMID: 14636592
MunsterKuhnel04: Munster-Kuhnel AK, Tiralongo J, Krapp S, Weinhold B, Ritz-Sedlacek V, Jacob U, Gerardy-Schahn R (2004). "Structure and function of vertebrate CMP-sialic acid synthetases." Glycobiology 14(10);43R-51R. PMID: 15201214
RevillaNuin98: Revilla-Nuin B, Reglero A, Feo JC, Rodriguez-Aparicio LB, Ferrero MA (1998). "Identification, expression and tissue distribution of cytidine 5'-monophosphate N-acetylneuraminic acid synthetase activity in the rat." Glycoconj J 15(3);233-41. PMID: 9579800
RodriguezAparic92: Rodriguez-Aparicio LB, Luengo JM, Gonzalez-Clemente C, Reglero A (1992). "Purification and characterization of the nuclear cytidine 5'-monophosphate N-acetylneuraminic acid synthetase from rat liver." J Biol Chem 267(13);9257-63. PMID: 1577759
Vionnet99: Vionnet J, Concepcion N, Warner T, Zapata G, Hanover J, Vann WF (1999). "Purification of CMP-N-acetylneuraminic acid synthetase from bovine anterior pituitary glands." Glycobiology 9(5);481-7. PMID: 10207180
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