Enzymes
| UniProtKB help_outline | 11 proteins |
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- Name help_outline CDP-L-ribitol Identifier CHEBI:57608 Charge -2 Formula C14H23N3O15P2 InChIKeyhelp_outline DPJKHFICSGCNIR-HRENORGGSA-L SMILEShelp_outline C=1N(C(N=C(C1)N)=O)[C@@H]2O[C@@H]([C@H]([C@H]2O)O)COP(OP(OC[C@H]([C@H]([C@H](CO)O)O)O)(=O)[O-])(=O)[O-] 2D coordinates Mol file for the small molecule Search links Involved in 7 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline CDP Identifier CHEBI:58069 Charge -3 Formula C9H12N3O11P2 InChIKeyhelp_outline ZWIADYZPOWUWEW-XVFCMESISA-K SMILEShelp_outline Nc1ccn([C@@H]2O[C@H](COP([O-])(=O)OP([O-])([O-])=O)[C@@H](O)[C@H]2O)c(=O)n1 2D coordinates Mol file for the small molecule Search links Involved in 28 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:71579 | RHEA:71580 | RHEA:71581 | RHEA:71582 | |
|---|---|---|---|---|
| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
| UniProtKB help_outline |
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Publications
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The promiscuous binding pocket of SLC35A1 ensures redundant transport of CDP-ribitol to the Golgi.
Ury B., Potelle S., Caligiore F., Whorton M.R., Bommer G.T.
The glycoprotein α-dystroglycan helps to link the intracellular cytoskeleton to the extracellular matrix. A unique glycan structure attached to this protein is required for its interaction with extracellular matrix proteins such as laminin. Up to now, this is the only mammalian glycan known to con ... >> More
The glycoprotein α-dystroglycan helps to link the intracellular cytoskeleton to the extracellular matrix. A unique glycan structure attached to this protein is required for its interaction with extracellular matrix proteins such as laminin. Up to now, this is the only mammalian glycan known to contain ribitol phosphate groups. Enzymes in the Golgi apparatus use CDP-ribitol to incorporate ribitol phosphate into the glycan chain of α-dystroglycan. Since CDP-ribitol is synthesized in the cytoplasm, we hypothesized that an unknown transporter must be required for its import into the Golgi apparatus. We discovered that CDP-ribitol transport relies on the CMP-sialic acid transporter SLC35A1 and the transporter SLC35A4 in a redundant manner. These two transporters are closely related, but bulky residues in the predicted binding pocket of SLC35A4 limit its size. We hypothesized that the large binding pocket SLC35A1 might accommodate the bulky CMP-sialic acid and the smaller CDP-ribitol, whereas SLC35A4 might only accept CDP-ribitol. To test this, we expressed SLC35A1 with mutations in its binding pocket in SLC35A1 KO cell lines. When we restricted the binding site of SLC35A1 by introducing the bulky residues present in SLC35A4, the mutant transporter was unable to support sialylation of proteins in cells but still supported ribitol phosphorylation. This demonstrates that the size of the binding pocket determines the substrate specificity of SLC35A1, allowing a variety of cytosine nucleotide conjugates to be transported. The redundancy with SLC35A4 also explains why patients with SLC35A1 mutations do not show symptoms of α-dystroglycan deficiency. << Less