UDP-glucuronic acid and UDP-xylose are the sugar donors for proteoglycan glycosaminoglycan chains and for other glucuronidated and xylosylated molecules. UDP-glucose pyrophosphorylase (Ugp) makes UDP-glucose from glucose-1-phosphate and UTP, and UDP-glucose 6-dehydrogenase (Sugarless, sgl) oxidises it to UDP-glucuronic acid in the cytosol. The nucleotide-sugar transporter Fringe connection (frc) imports UDP-glucuronic acid and other UDP sugars into the ER and Golgi lumen, where UDP-glucuronic acid decarboxylase (Uxs) converts UDP-glucuronic acid to UDP-xylose. Sugarless and Fringe connection were identified genetically through their requirement for Wingless and other heparan sulfate proteoglycan-dependent signalling.
Boundary. The module ends with the nucleotide sugars; their use by glycosyltransferases (for example xylosyltransferase Oxt and the glucuronyltransferases) is in dmel_glycosaminoglycan_biosynthesis and other glycosylation modules. Ugp also supplies UDP-glucose for glycogen and trehalose synthesis. frc and sgl are in both FlyBase groups and appear once. Fringe connection transports several UDP sugars (UDP-glucuronic acid, UDP-GlcNAc, UDP-xylose and others); the annoton gives the UDP-glucuronate transport activity relevant here. Placing Uxs after import assumes a lumenal enzyme, as for its mammalian ortholog UXS1; the topology of fly Uxs has not been determined. FlyBase groups realized by this module: UDPGAB (FBgg0002049), UDPXYLB (FBgg0002054). Participants were generated from the FlyBase gene-group membership and mapped to UniProtKB by projects/FLYBASE_GENE_GROUPS/generate_modules.py from module_specs/dmel_udp_glucuronate_xylose_biosynthesis.yaml. Member genes with a gene review in this repository: frc, sgl, Ugp, Uxs.
All recommended fields populated.
✗ none found
No MODULE:dmel_udp_glucuronate_xylose_biosynthesis deep-research report alongside the module YAML.
✓ every leaf node grounds to a representative protein.
✓ every declared conforms_to bundle matches its template motif.
✓ every PRECEDES step chains, or its break is acknowledged via chaining_status.
4 gene-function check(s) reflected in core functions · 0 conflict(s) · 0 evidence or coverage gap(s) (4 comparison(s))
Retained noncore functions are reported separately; they do not require promotion to core functions. Support from representative genes does not establish conservation across the whole family. Missing reviews or identifiers leave a claim unverified.
| Annoton | Participant | Function | Assessment |
|---|---|---|---|
| udp_glucose_synthesis_ugp | Ugp UniProtKB:Q9VSW1 Gene |
UTP:glucose-1-phosphate uridylyltransferase activity GO:0003983 |
Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass). |
| udp_glucose_oxidation_sgl | sgl UniProtKB:O02373 Gene |
UDP-glucose 6-dehydrogenase activity GO:0003979 |
Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass). |
| udp_sugar_import_frc | frc UniProtKB:Q95YI5 Gene |
UDP-glucuronate transmembrane transporter activity GO:0005461 |
Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass). |
| udp_glucuronate_decarboxylation_uxs | Uxs UniProtKB:Q9VSE8 Gene |
UDP-glucuronate decarboxylase activity GO:0048040 |
Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass). |
3 complete review(s) · 4 with deep research · 0 missing review · 0 reviewed but lacking deep research
| Gene | Review | Complete | Deep research |
|---|---|---|---|
| frc Q95YI5 | ✓ | 35/41 | ✓ |
| sgl O02373 | ✓ | ✓ | ✓ |
| Ugp Q9VSW1 | ✓ | ✓ | ✓ |
| Uxs Q9VSE8 | ✓ | ✓ | ✓ |
Synthesis of UDP-glucuronic acid and UDP-xylose from glucose-1-phosphate and their supply to the secretory pathway.