Enzymes
| UniProtKB help_outline | 3 proteins |
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- Name help_outline CMP Identifier CHEBI:60377 Charge -2 Formula C9H12N3O8P InChIKeyhelp_outline IERHLVCPSMICTF-XVFCMESISA-L SMILEShelp_outline Nc1ccn([C@@H]2O[C@H](COP([O-])([O-])=O)[C@@H](O)[C@H]2O)c(=O)n1 2D coordinates Mol file for the small molecule Search links Involved in 151 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline CMP-N-acetyl-β-neuraminate Identifier CHEBI:57812 (Beilstein: 5899715) help_outline Charge -2 Formula C20H29N4O16P InChIKeyhelp_outline TXCIAUNLDRJGJZ-BILDWYJOSA-L SMILEShelp_outline [H][C@]1(O[C@](C[C@H](O)[C@H]1NC(C)=O)(OP([O-])(=O)OC[C@H]1O[C@H]([C@H](O)[C@@H]1O)n1ccc(N)nc1=O)C([O-])=O)[C@H](O)[C@H](O)CO 2D coordinates Mol file for the small molecule Search links Involved in 72 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:67724 | RHEA:67725 | RHEA:67726 | RHEA:67727 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Publications
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Inhibition of CMP-sialic acid transport into Golgi vesicles by nucleoside monophosphates.
Chiaramonte M., Koviach J.L., Moore C., Iyer V.V., Wagner C.R., Halcomb R.L., Miller W., Melancon P., Kuchta R.D.
We examined the interactions of nucleotides with the CMP-sialic acid transporter in order to better understand which features play a role in binding and to investigate the relationship between binding and subsequent transport. With respect to the sugar, the transporter requires a complete ribose r ... >> More
We examined the interactions of nucleotides with the CMP-sialic acid transporter in order to better understand which features play a role in binding and to investigate the relationship between binding and subsequent transport. With respect to the sugar, the transporter requires a complete ribose ring for tight binding, and the 2'-ara hydrogen makes an important contact. The enzyme exhibits little specificity with respect to the 2'- and 3'-hydroxyls, as it tolerated substitutions ranging from fluorine to an azido group. In the base, the C4 amine and C2 carbonyl groups make important contacts, while the N3 nitrogen does not. However, adding a methyl group to N3 dramatically reduced binding, indicating that mass at this position sterically hinders binding. Adding a group at C5 had either no effect or slightly enhanced binding. To determine if the transporter recognizes these CMP analogues as substrates, we assayed them for their ability to trans stimulate CMP-sialic acid import. These data suggest that the enzyme transports a wide variety of NMPs, and the rate of transport is inversely proportional to the K(I) of the analogue. The importance of our findings for understanding the specificities of the different nucleotide-sugar tranlocators and the design of novel glycosylation inhibitors are discussed. << Less
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Structural basis for mammalian nucleotide sugar transport.
Ahuja S., Whorton M.R.
Nucleotide-sugar transporters (NSTs) are critical components of the cellular glycosylation machinery. They transport nucleotide-sugar conjugates into the Golgi lumen, where they are used for the glycosylation of proteins and lipids, and they then subsequently transport the nucleotide monophosphate ... >> More
Nucleotide-sugar transporters (NSTs) are critical components of the cellular glycosylation machinery. They transport nucleotide-sugar conjugates into the Golgi lumen, where they are used for the glycosylation of proteins and lipids, and they then subsequently transport the nucleotide monophosphate byproduct back to the cytoplasm. Dysregulation of human NSTs causes several debilitating diseases, and NSTs are virulence factors for many pathogens. Here we present the first crystal structures of a mammalian NST, the mouse CMP-sialic acid transporter (mCST), in complex with its physiological substrates CMP and CMP-sialic acid. Detailed visualization of extensive protein-substrate interactions explains the mechanisms governing substrate selectivity. Further structural analysis of mCST's unique lumen-facing partially-occluded conformation, coupled with the characterization of substrate-induced quenching of mCST's intrinsic tryptophan fluorescence, reveals the concerted conformational transitions that occur during substrate transport. These results provide a framework for understanding the effects of disease-causing mutations and the mechanisms of this diverse family of transporters. << Less
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Structural basis for the delivery of activated sialic acid into Golgi for sialyation.
Nji E., Gulati A., Qureshi A.A., Coincon M., Drew D.
The decoration of secretory glycoproteins and glycolipids with sialic acid is critical to many physiological and pathological processes. Sialyation is dependent on a continuous supply of sialic acid into Golgi organelles in the form of CMP-sialic acid. Translocation of CMP-sialic acid into Golgi i ... >> More
The decoration of secretory glycoproteins and glycolipids with sialic acid is critical to many physiological and pathological processes. Sialyation is dependent on a continuous supply of sialic acid into Golgi organelles in the form of CMP-sialic acid. Translocation of CMP-sialic acid into Golgi is carried out by the CMP-sialic acid transporter (CST). Mutations in human CST are linked to glycosylation disorders, and CST is important for glycopathway engineering, as it is critical for sialyation efficiency of therapeutic glycoproteins. The mechanism of how CMP-sialic acid is recognized and translocated across Golgi membranes in exchange for CMP is poorly understood. Here we have determined the crystal structure of a Zea mays CST in complex with CMP. We conclude that the specificity of CST for CMP-sialic acid is established by the recognition of the nucleotide CMP to such an extent that they are mechanistically capable of both passive and coupled antiporter activity. << Less
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Substrate recognition by nucleotide sugar transporters: further characterization of substrate recognition regions by analyses of UDP-galactose/CMP-sialic acid transporter chimeras and biochemical analysis of the substrate specificity of parental and chimeric transporters.
Aoki K., Ishida N., Kawakita M.
Human UDP-Gal transporter 1 (hUGT1) and the human CMP-Sia transporter (hCST) are similar in structure, with amino acid sequences that are 43% identical, but they have quite distinct transport substrates. To define their substrate recognition regions, we constructed various chimeras between the two ... >> More
Human UDP-Gal transporter 1 (hUGT1) and the human CMP-Sia transporter (hCST) are similar in structure, with amino acid sequences that are 43% identical, but they have quite distinct transport substrates. To define their substrate recognition regions, we constructed various chimeras between the two transporters and demonstrated that distinct submolecular regions of the transporter molecules are involved in the specific recognition of UDP-Gal and CMP-Sia (Aoki, K., Ishida, N., and Kawakita, M. (2001) J. Biol. Chem. 276, 21555-21561). In a further attempt to define the minimum submolecular regions required for the recognition of specific substrates, we found that substitution of helix 7 of hCST into the corresponding part of hUGT1 was necessary and sufficient for a chimera to show CST activity. Additional replacement of helix 2 or 3 of hUGT1 with the corresponding hCST sequence markedly increased the efficiency of CMP-Sia transport. For UGT activity, helices 1 and 8 of hUGT1 were necessary (but not sufficient), and helices 9 and 10 or helices 2, 3, and 7 derived from hUGT1 were also required to render the chimera competent for UDP-Gal transport. The in vitro analyses of a chimera with dual specificity indicated that it transported both UMP and CMP and mediated exchange reactions between these nucleotides and nucleotide sugars that are recognized specifically by either of the parental transporters. << Less
J. Biol. Chem. 278:22887-22893(2003) [PubMed] [EuropePMC]
This publication is cited by 13 other entries.