Apical-basal polarity complexes (Par, Crumbs, Scribble) in Drosophila melanogaster
Epithelial cells divide their plasma membrane into apical and basolateral domains using three conserved groups of polarity proteins that act on each other. The Par complex, Bazooka (Par-3), Par-6 and atypical protein kinase C (aPKC), marks the apical side and the adherens junction; aPKC phosphorylates basolateral proteins to exclude them from the apical membrane. The Crumbs complex, the transmembrane protein Crumbs with Stardust (PALS1) and Patj, defines the apical membrane above the adherens junction. The Scribble module, Scribble, Discs large (Dlg1) and Lethal (2) giant larvae (Lgl), acts basolaterally and restricts apical determinants. Mutual antagonism between apical and basolateral proteins sets the boundary, and loss of the Scribble module causes neoplastic overgrowth.
The Par complex also acts in neuroblast asymmetric division and the Scribble module in neuromuscular junction organization; this module describes their shared core composition. Other polarity regulators (Cdc42, Yurt, Coracle group, Par-1) are context and not parts. FlyBase groups realized by this module: PAR (FBgg0001760), SCRIBC (FBgg0001762), CRBC (FBgg0001763). 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_epithelial_polarity_complexes.yaml. None of the member genes has a gene review in this repository yet.
Derived QC
Recommended-field compliance
All recommended fields populated.
Module deep research
✗ none found
No MODULE:dmel_epithelial_polarity_complexes deep-research report alongside the module YAML.
Leaf nodes lacking representative members
✓ every leaf node grounds to a representative protein.
Template conformance
✓ every declared conforms_to bundle matches its template motif.
Function consistency and core coverage
0 gene-function check(s) reflected in core functions · 0 conflict(s) · 1 evidence or coverage gap(s) (1 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 |
|---|---|---|---|
| par_complex_complex/apkc | aPKC UniProtKB:A1Z9X0 Complex Unit |
protein serine/threonine kinase activity GO:0004674 |
Review Missing
No ai-review exists for this protein; its function and core-function coverage cannot yet be checked. |
Feedback loops (advisory, prose-driven: a regulator counts as "feedback" when its own description says so)
✓ every negative regulator described as feedback has an upstream edge closing the loop.
-
par_complex ⊣ scribble_module [closed]
par_complex is regulated by crumbs_complex: feedback loop closed -
scribble_module ⊣ par_complex [input]
scribble_module is a negative regulator with no upstream edge (not described as feedback)
Gene-review completeness (2/9 grounded genes reviewed)
1 complete review(s) · 2 with deep research · 7 missing review · 0 reviewed but lacking deep research
| Gene | Review | Complete | Deep research |
|---|---|---|---|
| aPKC A1Z9X0 | ✗ | — | — |
| crb P10040 | ✓ | ✓ | ✓ |
| dlg1 P31007 | ✓ | 97/98 | ✓ |
| sdt E2QD98 | ✗ | — | — |
| par-6 O97111 | ✗ | — | — |
| l(2)gl P08111 | ✗ | — | — |
| baz Q0KHR3 | ✗ | — | — |
| scrib Q7KRY7 | ✗ | — | — |
| Patj Q9NB04 | ✗ | — | — |
Details
Par, Crumbs and Scribble polarity complexes that set apical and basolateral membrane domains by mutual antagonism.
Connections
Annotons
Annotons
Locations
Scribble, Dlg1 and Lgl act together genetically and localize basolaterally, but are not known to form a single stable complex.