EcmA (also known as ST430 or Dd63) is a large, secreted, cysteine-rich extracellular matrix glycoprotein of the social amoeba Dictyostelium discoideum. The mature protein is dominated by dozens of tandem Cys-rich repeats (the Dictyostelium "CT"/Dicty_CTDC repeat) and carries a cleaved N-terminal signal peptide and numerous N-glycosylation sites, consistent with secretion into the extracellular space. EcmA is deposited as a structural constituent of the developmental extracellular matrix, contributing to the slime sheath that surrounds the migrating slug (pseudoplasmodium) and to the cellulose-rich stalk-tube matrix formed during culmination. Its expression is essentially confined to prestalk cells, chiefly the anterior-most prestalk zone, and is induced by the chlorinated stalk morphogen DIF-1 (differentiation-inducing factor). Because of this tightly regulated, cell-type-restricted expression, ecmA is a classic molecular marker for prestalk cell differentiation and is widely used (often as an ecmA/ecmAO promoter reporter) to follow prestalk fate, cell sorting, and morphogenesis in the Dictyostelium developmental cycle.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0031012 extracellular matrix | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetically inferred localization to the extracellular matrix. This is consistent with direct proteomic and experimental evidence that EcmA is a structural component of the Dictyostelium developmental ECM (slime sheath / stalk tube), and represents a core aspect of the protein. Reason: EcmA is a secreted extracellular-matrix protein; ECM localization is directly supported by proteomic profiling of the slime sheath, so the IBA inference is corroborated by primary evidence. Supporting Evidence: PMID:26152465 identified numerous expected (e.g. EcmA, EcmD, discoidin I, discoidin II) |
| GO:0099120 socially cooperative development | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Phylogenetic inference that EcmA participates in the multicellular (social) developmental program. EcmA is indeed a prestalk-expressed ECM protein deposited during slug and fruiting-body morphogenesis, so involvement in cooperative development is reasonable, but this is a very general process term that does not capture the protein's specific structural role. Reason: EcmA contributes to development only as a downstream structural ECM constituent of prestalk-derived matrix; the broad "socially cooperative development" term is correct in spirit but too general to represent the core molecular function. Supporting Evidence: PMID:41057014 During multicellular development, the ecmA and ecmB genes encode extracellular matrix proteins, which are mainly expressed in the most anterior prestalk cells of slugs and can regulate the morphogenesis of Dictyostelium |
| GO:0005576 extracellular region | IEA GO_REF:0000044 | ACCEPT | Summary: Electronic annotation from the UniProt "Secreted" subcellular location. EcmA has a cleaved signal peptide and is a bona fide secreted ECM protein, so extracellular localization is correct. Reason: The UniProt record documents a signal peptide and secreted location, and the protein is experimentally recovered from the extracellular slime sheath; extracellular-region localization is well supported. Supporting Evidence: PMID:26152465 identified numerous expected (e.g. EcmA, EcmD, discoidin I, discoidin II) |
| GO:0009642 response to light intensity | HEP PMID:41057014 Transcriptomic and metabolomic insights into light-mediated ... | KEEP AS NON CORE | Summary: High-throughput expression (HEP) annotation reflecting that ecmA transcript levels increase upon light exposure during the unicellular-to-multicellular transition. This captures the transcriptional responsiveness of the prestalk marker to light, not a mechanistic role for the EcmA protein in phototransduction. Reason: The annotation is based on ecmA being upregulated by light, i.e. it is a downstream transcriptional readout of prestalk differentiation, which is known to be light-sensitive. EcmA is a structural ECM protein and does not itself mediate the light response, so this is retained as a non-core, expression-based association. Supporting Evidence: PMID:41057014 Our findings revealed that both of ecmA and ecmB genes are upregulated when exposed to light |
| GO:0099120 socially cooperative development | IDA PMID:38561423 Prestalk-like positioning of de-differentiated cells in the ... | KEEP AS NON CORE | Summary: Direct assay annotation from a study of prestalk-like cell positioning during Dictyostelium development, in which ecmA (as an ecmAO reporter) was used as the prestalk cell-type marker and its expression tracked differentiation and de-differentiation. The annotation places EcmA within the cooperative developmental program. Reason: Per curation policy this experimental (IDA) annotation is retained. However, EcmA participates in cooperative development as a downstream, prestalk-restricted structural ECM constituent and differentiation marker, so the very general process term is best marked non-core rather than as the protein's core function. Supporting Evidence: PMID:38561423 Refed (RF) cells harbored prespore (pspA-GFP, green) and prestalk (ecmAO-RFP, magenta) markers. |
| GO:0031012 extracellular matrix | HDA PMID:26152465 Proteomic profiling of the extracellular matrix (slime sheat... | ACCEPT | Summary: High-throughput direct-assay (proteomic) localization of EcmA to the Dictyostelium extracellular matrix (slime sheath). LC/MS/MS of slug ECM recovered EcmA among the expected structural components, providing strong evidence for ECM localization. Reason: EcmA was directly identified by mass spectrometry in the purified slug ECM (slime sheath), confirming that the extracellular matrix is its site of deposition. This is a core localization for the protein. Supporting Evidence: PMID:26152465 identified numerous expected (e.g. EcmA, EcmD, discoidin I, discoidin II) |
| GO:0031154 culmination involved in sorocarp development | IEP PMID:25887420 Leaps and lulls in the developmental transcriptome of Dictyo... | KEEP AS NON CORE | Summary: Expression-pattern (IEP) annotation. In the developmental transcriptome, ecmA is induced during late development and upregulated dramatically around culmination (16-18 h), coincident with stalk/fruiting-body formation, consistent with a role for the prestalk ECM protein during culmination. Reason: The annotation rests on ecmA's culmination-phase expression as a prestalk gene rather than on a demonstrated mechanistic requirement of the EcmA protein for culmination. EcmA contributes to stalk-tube matrix formation, so involvement in culmination is plausible but retained as non-core given the expression-based evidence. Supporting Evidence: PMID:25887420 Expression of the prestalk genes ecmA, ecmB and ecmF ([19,36], could be detected as early as 12 h, but were up-regulated more dramatically between 16 h and 18 h |
| GO:1902168 response to catechin | IDA PMID:23516620 The green tea catechin epigallocatechin gallate (EGCG) block... | MARK AS OVER ANNOTATED | Summary: Annotation derived from a study showing that the green-tea catechin EGCG blocks Dictyostelium development, with near-complete loss of prestalk-specific ecmA (and prespore pspA) expression in treated cells. This reflects that ecmA expression is suppressed when development is blocked by catechin, not that EcmA has a dedicated function in a catechin-response pathway. Reason: The evidence is that ecmA transcription is downregulated as a nonspecific consequence of EGCG-induced developmental arrest (a general differentiation-marker readout), not that EcmA functions in "response to catechin." Treating this as a biological function of the protein over-interprets a downstream transcriptional effect. Supporting Evidence: PMID:23516620 we detected almost no expression of prespore specific pspA and prestalk specific ecmA genes in EGCG treated cells at 10 to 12 h into starvation |
| GO:0005198 structural molecule activity | TAS PMID:8016318 Prestalk cell-differentiation and movement during the morpho... | ACCEPT | Summary: Traceable-author annotation assigning EcmA a structural molecule activity. As a secreted, Cys-rich repeat glycoprotein deposited in the slime sheath and stalk-tube matrix, EcmA acts as a structural constituent of the developmental ECM; this is the best representation of its core molecular function. Reason: EcmA is an abundant structural ECM protein with no known catalytic activity; structural molecule activity correctly captures its core molecular role as a matrix building block. Supporting Evidence: PMID:41057014 During multicellular development, the ecmA and ecmB genes encode extracellular matrix proteins, which are mainly expressed in the most anterior prestalk cells of slugs and can regulate the morphogenesis of Dictyostelium |
| GO:0030198 extracellular matrix organization | TAS PMID:8016318 Prestalk cell-differentiation and movement during the morpho... | ACCEPT | Summary: Traceable-author annotation that EcmA participates in organizing the extracellular matrix. As a structural constituent deposited into the slime sheath and stalk tube, EcmA contributes to assembly/organization of the developmental ECM. Reason: EcmA is deposited into and helps constitute the developmental ECM whose assembly accompanies slug and stalk morphogenesis; extracellular matrix organization is an appropriate biological-process annotation for a core matrix component. Supporting Evidence: PMID:41057014 During multicellular development, the ecmA and ecmB genes encode extracellular matrix proteins, which are mainly expressed in the most anterior prestalk cells of slugs and can regulate the morphogenesis of Dictyostelium |
| GO:0031012 extracellular matrix | TAS PMID:8016318 Prestalk cell-differentiation and movement during the morpho... | ACCEPT | Summary: Traceable-author localization of EcmA to the extracellular matrix, consistent with all other evidence (proteomic recovery from the slime sheath, secreted status). This is a core localization. Reason: ECM localization of EcmA is corroborated by direct proteomic evidence and its secreted nature; the TAS annotation is accurate. Supporting Evidence: PMID:26152465 identified numerous expected (e.g. EcmA, EcmD, discoidin I, discoidin II) |
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