BMP ligands activate type I and type II serine/threonine kinase receptor complexes that phosphorylate SMAD1/5-family effectors and regulate developmental patterning and differentiation.
Curated compact signaling-pathway module generated from verified UniProt exemplar accessions and local PAINT IBD rows. PTN anchors are included only when the exemplar accession appears in an IBD seed row in interpro/panther; roles without local PAINT seeds remain grounded by verified UniProt exemplar accessions. Nuclear entry step (2026-11-05): added R-SMAD/SMAD4 complex formation and SMAD nuclear import (by module_ref to karyopherin_nuclear_protein_import), so that the module states the steps GO-CAM BMP models compress into a receptor -> nuclear SMAD edge; GO-CAM activities realizing the receptor and SMAD steps are pinned with gocam_associations. Falcon integration (2026-06-28): Falcon findings are linked as evidence and family-level support. Automatically extracted open-question headings were intentionally not retained as knowledge_gap entries because they were not manually curated. Machine-generated Falcon citations remain curation support and are not manually adjudicated here.
All recommended fields populated.
✓ present
✓ 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.
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 |
|---|---|---|---|
| smad4_complex_partner | SMAD4 UniProtKB:Q13485 Gene |
R-SMAD binding GO:0070412 |
Annotation Supported
A retained annotation or curated replacement supports this function, but core_functions does not yet reflect it. |
0 complete review(s) · 0 with deep research · 2 missing review · 4 reviewed but lacking deep research
| Gene | Review | Complete | Deep research |
|---|---|---|---|
| BMP4 P12644 | ✓ | 143/209 | ✗ |
| BMPR1A P36894 | ✓ | 130/140 | ✗ |
| BMPR2 Q13873 | ✓ | 114/152 | ✗ |
| SMAD1 Q15797 | ✗ | — | — |
| SMAD5 Q99717 | ✗ | — | — |
| SMAD4 Q13485 | ✓ | 422/428 | ✗ |
BMP4 ligand engages BMPR type I and type II receptor chains.
Curated exemplar for the bmp4 ligand role in BMP signaling pathway.
Curated exemplar for the bmpr1a type i receptor role in BMP signaling pathway.
Curated exemplar for the bmpr2 type ii receptor role in BMP signaling pathway.
BMP receptors phosphorylate receptor-regulated SMAD1 and SMAD5.
Curated exemplar for the smad1 receptor-regulated smad role in BMP signaling pathway.
Curated exemplar for the smad5 receptor-regulated smad role in BMP signaling pathway.
Receptor-phosphorylated SMAD1/5/9 leave the receptor, bind the common mediator SMAD4, and accumulate in the nucleus. GO-CAM models compress this into a single edge from a plasma-membrane type I receptor kinase to a nuclear SMAD transcription factor activity (see projects/GOCAM_COMPARTMENTS.md). Two other gene products are needed: SMAD4, a pathway-specific partner, and the import machinery (importin-7/8 and importin-beta1 with the Ran system), included here by reference.
Phosphorylated SMAD1/5/9 bind SMAD4 in response to BMP. SMAD4 is required for BMP-SMAD transcriptional responses.
Binds receptor-phosphorylated SMAD1/5/9 to form the heteromeric complex that enters the nucleus.
Activated SMAD complexes are carried into the nucleus directly by importin-beta-family carriers (importin-7 and importin-8; the SMAD MH1 basic motif is required), without an importin-alpha adaptor.
Realized by module
karyopherin_nuclear_protein_import
SMAD4 complexes relay BMP receptor activation to nuclear transcriptional responses.
Curated exemplar for the smad4 common mediator role in BMP signaling pathway.
Curated exemplar for the smad1 transcriptional effector role in BMP signaling pathway.