Dictyostelium developmental cell-cell adhesion and tgr allorecognition

The developmentally staged cell-cell adhesion systems of Dictyostelium discoideum, culminating in tgr-locus allorecognition. As starving cells enter development they deploy successive adhesion molecules: (1) the Ca2+-dependent adhesion molecule ddCAD-1 (cadA), which mediates EDTA-sensitive homophilic adhesion at the loose-aggregate stage; (2) the contact-sites-A glycoprotein csA/gp80 (csaA), which mediates EDTA-resistant (Ca2+-independent) homophilic adhesion during tight aggregation; and (3) the polymorphic Tiger proteins TgrC1 (the ligand) and TgrB1 (the receptor), a heterophilic self-recognition pair required for post-aggregation adhesion and kin discrimination — cells bearing matching tgrB1/tgrC1 alleles cooperate, enabling coordinated multicellular development and excluding non-kin. This is a set of parallel, developmentally ordered adhesion systems rather than a linear pathway, so it is modelled as staged PRECEDES steps. OUT OF SCOPE: the intracellular actin cytoskeleton coupling of adhesion, and the other ~12 tgr paralogs at the tgr locus (only the reviewed tgrB1/tgrC1 pair is grounded). Note tgrC1 = lagC/gp150.

MODULE:dicty_allorecognition_adhesionDRAFTDevelopmental Processmodules/dicty_allorecognition_adhesion.yaml
aggregation involved in sorocarp developmentGO:0031152
GO:0031152
aggregation involved in sorocarp development
These adhesion systems operate during aggregation and post-aggregation (GO:0031152), holding cells together as the mound forms.
file:DICDI/cadA/cadA-ai-review.yaml
cadA gene review (Dictyostelium discoideum)
Early Ca2+-dependent adhesion grounding (UniProtKB:P54657, GO:0042802 identical protein binding; ddCAD-1 homophilic adhesion).
file:DICDI/csaA/csaA-ai-review.yaml
csaA gene review (Dictyostelium discoideum)
Aggregation-stage Ca2+-independent adhesion grounding (UniProtKB:P08796, GO:0098632 cell-cell adhesion mediator activity; csA/gp80).
file:DICDI/tgrC1/tgrC1-ai-review.yaml
tgrC1 gene review (Dictyostelium discoideum)
Allorecognition ligand + post-aggregation adhesion grounding (UniProtKB:P42523, GO:0048018 receptor ligand activity; = lagC/gp150).
file:DICDI/tgrB1/tgrB1-ai-review.yaml
tgrB1 gene review (Dictyostelium discoideum)
Allorecognition receptor grounding (UniProtKB:Q54V07, GO:0004888 transmembrane signaling receptor activity); binds TgrC1.

Dictyostelium-specific staged-adhesion / allorecognition module grounded to ddCAD-1 (P54657), csA (P08796), TgrC1 (P42523) and TgrB1 (Q54V07). GO molecular-function terms were taken from the completed DICDI reviews; nodes use PANTHER family selectors plus D. discoideum representative members. Modelled as three PRECEDES-ordered developmental stages (early Ca2+-dependent -> aggregation Ca2+-independent -> post-aggregation allorecognition) rather than a linear biochemical pathway. Only the reviewed tgrB1/tgrC1 pair is grounded; the wider polymorphic tgr locus is out of scope. Named to signal Dictyostelium scope.

4Nodes
3Parts
0Variant Sets
0Variants
4Annotons
2Connections

Derived QC

Recommended-field compliance

100.0% recommended fields populated

All recommended fields populated.

Module deep research

✗ none found

No MODULE:dicty_allorecognition_adhesion 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.

Reaction chaining (advisory)

✓ every PRECEDES step chains, or its break is acknowledged via chaining_status.

  • cada_adhesion → csa_adhesion [NOT_CHECKED]
  • csa_adhesion → tgr_allorecognition [NOT_CHECKED]

Gene-review completeness (4/4 grounded genes reviewed)

2 complete review(s) · 0 with deep research · 0 missing review · 4 reviewed but lacking deep research

Gene Review Complete Deep research
cadA P54657 ✓ 42/43 ✗
csaA P08796 ✓ ✓ ✗
tgrB1 Q54V07 ✓ 13/15 ✗
tgrC1 P42523 ✓ ✓ ✗

Details

Developmental adhesion and allorecognition (ddCAD-1 -> csA -> TgrB1/TgrC1)Developmental Processdicty_allorecognition_adhesion
aggregation involved in sorocarp developmentGO:0031152

Connections

Ca2+-dependent ddCAD-1 adhesion at the early aggregate stage precedes the Ca2+-independent csA adhesion of tight aggregation.
csA-mediated aggregation adhesion precedes the post-aggregation TgrB1-TgrC1 allorecognition adhesion.
Part 1: early Ca2+-dependent homophilic adhesion
ddCAD-1 (cadA) Ca2+-dependent homophilic adhesionRegulatory Stepcada_adhesion

Annotons

ddCAD-1 (cadA): Ca2+-dependent cell adhesion molecule
cada_activity
Participant: Family: Calcium-dependent cell adhesion molecule family (ddCAD-1)
Family:
Calcium-dependent cell adhesion molecule family (ddCAD-1)PANTHER:PTHR38083
Representative Members: ddCAD-1 (Dictyostelium discoideum)UniProtKB:P54657

Function

identical protein bindingGO:0042802

Locations

external side of plasma membraneGO:0009897

Calcium-dependent adhesion molecule mediating EDTA-sensitive homophilic adhesion at the early loose-aggregate stage; unconventionally exported via the contractile vacuole.

Part 2: aggregation-stage Ca2+-independent homophilic adhesion
csA/gp80 (csaA) Ca2+-independent homophilic adhesionRegulatory Stepcsa_adhesion

Annotons

csA/gp80 (csaA): contact sites A adhesion glycoprotein
csa_activity
Participant: Family: IPT/TIG-domain adhesion glycoprotein family (csA/Tgr)
Family:
IPT/TIG-domain adhesion glycoprotein family (csA/Tgr)PANTHER:PTHR31341
Representative Members: csA (Dictyostelium discoideum)UniProtKB:P08796

Function

cell-cell adhesion mediator activityGO:0098632

Locations

external side of plasma membraneGO:0009897

GPI-anchored contact-sites-A glycoprotein mediating EDTA-resistant (Ca2+-independent) homophilic adhesion during tight aggregation.

Part 3: post-aggregation adhesion and tgr allorecognition
TgrB1-TgrC1 heterophilic self-recognition adhesion complexProtein Complextgr_allorecognition

Annotons

TgrC1 (=lagC/gp150): allorecognition ligand
tgrc1_activity
Participant: Family: IPT/TIG-domain Tiger protein family (Tgr)
Family:
IPT/TIG-domain Tiger protein family (Tgr)PANTHER:PTHR31341
Representative Members: TgrC1 (Dictyostelium discoideum)UniProtKB:P42523

Function

receptor ligand activityGO:0048018

Locations

external side of plasma membraneGO:0009897

Polymorphic cell-surface ligand for TgrB1; also provides post-aggregation adhesion. Matching alleles enable kin cooperation.

TgrB1: allorecognition receptor
tgrb1_activity
Participant: Family: IPT/TIG-domain Tiger protein family (Tgr)
Family:
IPT/TIG-domain Tiger protein family (Tgr)PANTHER:PTHR31341
Representative Members: TgrB1 (Dictyostelium discoideum)UniProtKB:Q54V07

Function

transmembrane signaling receptor activityGO:0004888

Locations

plasma membraneGO:0005886

Polymorphic transmembrane receptor that binds partner TgrC1; allele-matched TgrB1-TgrC1 recognition licenses coordinated multicellular development (kin discrimination).