AAMP (angio-associated migratory cell protein) is a 52 kDa WD40-repeat protein that also carries immunoglobulin-like domains and an N-terminal basic heparin-binding region. It occupies two pools: an intracellular cytosolic pool and a plasma-membrane/cell-surface pool, the latter mediating high-affinity heparin binding and heparin-sensitive, glycosaminoglycan-dependent cell adhesion. Functionally AAMP is a positive regulator of Rho-family small GTPases and hence of actin-based motility. It binds RhoA directly and shields it from SMURF2-mediated ubiquitination and degradation, raising the pool of active RhoA, and it binds CDC42 and promotes its activation, driving formation of cellular protrusions. Through RhoA/Rho-kinase signalling AAMP is required for VEGF-induced endothelial cell spreading, migration, actin stress-fibre formation and tube formation, and for smooth muscle cell migration and neointima formation after arterial injury; antibody blockade of surface AAMP inhibits both. It is expressed in endothelial cells, trophoblasts, smooth muscle and many tumours, and its upregulation promotes migration and invasion in colorectal and non-small-cell lung cancer. Separately from its cytoskeletal role, its WD40 domains engage the innate-immune receptor NOD2 and modulate NOD1/NOD2-driven NF-kappaB activation. In endothelial cells AAMP is itself a short-lived, ubiquitination-controlled protein and acts as a negative regulator of barrier function: its depletion lowers RhoA and RhoB activity and raises trans-endothelial electrical resistance.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0014909 smooth muscle cell migration | IBA GO_REF:0000033 | ACCEPT | Summary: The WITH/FROM field of this IBA is PANTHER:PTN001068868|UniProtKB:Q13685, and Q13685 is human AAMP itself - the gene being annotated. That self-reference is not a defect. As clarified by the repository maintainer during review, a self-referential IBA is a valid and meaningful curation act: it records that the PAINT curator inspected the source annotation, judged the function to be core rather than peripheral, and found the assignment evolutionarily coherent, with an IBD supporting it further up the tree. The IBA is therefore an independent curatorial judgement layered on top of the experimental annotation, not a circular restatement of it. The underlying biology is well demonstrated in any case: overexpression increases smooth muscle cell migration, antibody treatment and siRNA decrease it, and antibody blockade reduces neointima formation in apoE-null mice. Accept as a core process. Reason: Correct and core. The self-reference in WITH/FROM reflects a curator judging this function core for the family node, which is the intended use of IBA, not a propagation failure. Propagation Review Root cause: NO FAILURE CORE Sources checked: UniProtKB:Q13685 Human AAMP - the gene being annotated. Its appearance in its own IBA's WITH/FROM records the curator's judgement that this is a core function of the family node, supported by an IBD further up the tree. PANTHER:PTN001068868 AAMP family node from which the phylogenetic assignment was made. Supporting Evidence: PMID:18634987 The AAMP overexpression increases, while both treatment with anti-rAAMP-ab and transfection with siRNA decreases SMC migration. |
| GO:0005737 cytoplasm | IEA GO_REF:0000044 | ACCEPT | Summary: Electronic mapping from the UniProt "Cytoplasm" subcellular location. Correct: AAMP has a substantial intracellular pool, which is where it engages RhoA and CDC42. Supporting Evidence: file:human/AAMP/AAMP-uniprot.txt SUBCELLULAR LOCATION: Cell membrane. Cytoplasm. |
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | ACCEPT | Summary: Electronic mapping from the UniProt "Cell membrane" subcellular location. Correct and functionally important: the membrane and surface pool is where heparin binding and heparin-sensitive adhesion occur, and where blocking antibodies act to inhibit endothelial tube formation and smooth muscle migration. Supporting Evidence: file:human/AAMP/AAMP-uniprot.txt SUBCELLULAR LOCATION: Cell membrane. Cytoplasm. |
| GO:0005515 protein binding | IPI PMID:28514442 Architecture of the human interactome defines protein commun... | MARK AS OVER ANNOTATED | Summary: Interaction with AEN (UniProtKB:Q8WTP8-2), an apoptosis-enhancing exonuclease, from a large-scale interactome study. All four protein-binding annotations on this gene report this same partner, and none has any functional follow-up or described mechanistic connection to AAMP. Strikingly, none of the four recovered RHOA, RHOB, CDC42 or NOD2 - every partner for which AAMP's mechanism has been worked out and which is citable here - so the GOA binding record is disjoint from the gene's characterised interactions. Bare "protein binding" conveys nothing in any case. Reason: Uninformative term for a high-throughput hit with no functional follow-up. Not removed: the pair was recovered by several screens, so it may yet prove real. Supporting Evidence: PMID:34901393 AAMP stabilized RhoA by binding to it and suppressing its SMURF2-mediated ubiquitination and degradation. |
| GO:0005515 protein binding | IPI PMID:29892012 An interactome perturbation framework prioritizes damaging m... | MARK AS OVER ANNOTATED | Summary: Interaction with AEN (UniProtKB:Q8WTP8) from an interactome perturbation study. Same assessment as the other AEN entries: reproducible across screens but functionally uncharacterised, and recorded under an uninformative term. Reason: Uninformative term for a high-throughput hit with no functional follow-up. Supporting Evidence: PMID:34901393 AAMP stabilized RhoA by binding to it and suppressing its SMURF2-mediated ubiquitination and degradation. |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | MARK AS OVER ANNOTATED | Summary: Interaction with AEN (UniProtKB:Q8WTP8-2) in the human binary interactome reference map. Same assessment as the other AEN entries. Reason: Uninformative term for a high-throughput hit with no functional follow-up. Supporting Evidence: PMID:34901393 AAMP stabilized RhoA by binding to it and suppressing its SMURF2-mediated ubiquitination and degradation. |
| GO:0005515 protein binding | IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling... | MARK AS OVER ANNOTATED | Summary: Interaction with AEN (UniProtKB:Q8WTP8) from the BioPlex AP-MS interactome - an orthogonal method to the two-hybrid screens, which does strengthen the case that the pair is real. It remains functionally uncharacterised and recorded under an uninformative term. Reason: Uninformative term for a high-throughput hit with no functional follow-up. Supporting Evidence: PMID:34901393 AAMP stabilized RhoA by binding to it and suppressing its SMURF2-mediated ubiquitination and degradation. |
| GO:0005829 cytosol | IDA GO_REF:0000052 | ACCEPT | Summary: Direct immunofluorescence localisation (Human Protein Atlas) to the cytosol. Consistent with UniProt and with the intracellular RhoA/CDC42-regulating activity. Core location. Supporting Evidence: file:human/AAMP/AAMP-uniprot.txt SUBCELLULAR LOCATION: Cell membrane. Cytoplasm. |
| GO:0005886 plasma membrane | IDA GO_REF:0000052 | ACCEPT | Summary: Direct immunofluorescence localisation to the plasma membrane, corroborating the UniProt "Cell membrane" location by an independent route. Core location, and the compartment in which AAMP was reported to be enriched in neointima-derived smooth muscle cells. Supporting Evidence: file:human/AAMP/AAMP-uniprot.txt SUBCELLULAR LOCATION: Cell membrane. Cytoplasm. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-9674529 | ACCEPT | Summary: Cytosolic location asserted by the Reactome reaction "AAMP binds to TBXA2R". Correct compartment; the annotation is a by-product of Reactome modelling a specific binding event rather than independent localisation evidence. Supporting Evidence: file:human/AAMP/AAMP-uniprot.txt SUBCELLULAR LOCATION: Cell membrane. Cytoplasm. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-9674531 | ACCEPT | Summary: Cytosolic location from the Reactome reaction "AAMP binds EGFR". Same assessment as the other Reactome-derived cytosol annotations. Supporting Evidence: file:human/AAMP/AAMP-uniprot.txt SUBCELLULAR LOCATION: Cell membrane. Cytoplasm. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-9674532 | ACCEPT | Summary: Cytosolic location from the Reactome reaction "AAMP gene expression is positively regulated by VEGF". Consistent with PMID:26350504, which showed VEGF upregulates AAMP and recruits it to membrane protrusions. Correct compartment. Supporting Evidence: file:human/AAMP/AAMP-uniprot.txt SUBCELLULAR LOCATION: Cell membrane. Cytoplasm. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-9676160 | ACCEPT | Summary: Cytosolic location from the Reactome reaction "AAMP binds NOD2", which models the innate-immune arm of AAMP function reported in PMID:19535145. Correct compartment for a cytosolic NLR interaction. Supporting Evidence: file:human/AAMP/AAMP-uniprot.txt SUBCELLULAR LOCATION: Cell membrane. Cytoplasm. |
| GO:0008201 heparin binding | IDA PMID:7743515 Identification of a new immunoglobulin superfamily protein e... | ACCEPT | Summary: Well supported and quantitative: the AAMP-derived peptide P189 contains a heparin-binding domain with a dissociation constant of 14 pmol and mediates heparin-sensitive cell adhesion. This is one of only two molecular functions AAMP has, and the one that explains its surface activity. Core molecular function. Supporting Evidence: PMID:7743515 The AAMP-derived peptide, P189, contains a heparin-binding domain (dissociation constant, 14 pmol) and mediates heparin-sensitive cell adhesion. |
| GO:0001525 angiogenesis | NAS PMID:10329261 Angio-associated migratory cell protein is expressed as an e... | ACCEPT | Summary: Annotated NAS (non-traceable author statement), which understates the current evidence. AAMP's role in angiogenesis is now directly demonstrated: siRNA knockdown and antibody blockade impair VEGF-induced endothelial cell tube formation and aortic ring sprouting, and anti-AAMP antibody blocks endothelial tube formation on Matrigel. The term is correct and core; only the evidence code is weaker than the literature now warrants. Supporting Evidence: PMID:26350504 Furthermore, we identified RhoA/Rho kinase signaling as an important factor that contributes to the action of AAMP in regulating endothelial cell migration and angiogenesis. file:human/AAMP/AAMP-uniprot.txt FUNCTION: Plays a role in angiogenesis and cell migration. In smooth |
| GO:0009986 cell surface | IDA PMID:10329261 Angio-associated migratory cell protein is expressed as an e... | ACCEPT | Summary: AAMP is expressed as an extracellular protein by blood-vessel-associated mesenchymal cells. The surface pool is functionally meaningful rather than incidental: it is the target of the blocking antibodies that inhibit endothelial tube formation and smooth muscle migration, and the site of heparin-sensitive adhesion. Core location. Note the caveat added by PMID:39404373: in a confluent endothelial monolayer, ectopically expressed AAMP was seen in nucleus and cytosol but not at the plasma membrane, so the surface pool may be context-dependent rather than constitutive. Supporting Evidence: PMID:7743515 first isolated from a human melanoma cell line during a search for motility-associated cell surface proteins. |
| GO:0010595 positive regulation of endothelial cell migration | ISS GO_REF:0000024 | ACCEPT | Summary: Sequence-similarity transfer from bovine AAMP (UniProtKB:Q3SZK1). Unusually, the human gene has stronger direct evidence than the ortholog this was transferred from: AAMP knockdown and antibody blockade impair VEGF-induced human endothelial cell spreading, migration and tube formation, acting through RhoA/Rho-kinase. The term is correct and core; like the angiogenesis NAS, the evidence code understates what is known. Supporting Evidence: PMID:26350504 Furthermore, we identified RhoA/Rho kinase signaling as an important factor that contributes to the action of AAMP in regulating endothelial cell migration and angiogenesis. |
| GO:0014909 smooth muscle cell migration | IEP PMID:18634987 Blockade of angio-associated migratory cell protein inhibits... | ACCEPT | Summary: Correct term, but the IEP evidence code substantially understates its own source. PMID:18634987 is not an expression-correlation study: AAMP overexpression increased smooth muscle cell migration while antibody treatment and siRNA decreased it, knockdown reduced membrane-fraction RhoA activity, and antibody blockade reduced neointimal smooth muscle cell density and neointima formation in apoE-null mice without affecting proliferation. That is direct perturbation evidence - IMP - not an expression pattern. Accepted as a core process; the evidence-code question is raised in suggested_questions for the responsible curator rather than silently re-coded here. Supporting Evidence: PMID:18634987 The AAMP overexpression increases, while both treatment with anti-rAAMP-ab and transfection with siRNA decreases SMC migration. PMID:18634987 Knockdown of AAMP decreases RhoA activity in the membrane fraction of SMCs. |
| GO:0031267 small GTPase binding | IPI PMID:34901393 AAMP promotes colorectal cancermetastasis by suppressing SMU... | NEW | Summary: Proposed new annotation. Apart from heparin binding, AAMP currently has no molecular function in GOA, so nothing in the record connects it to the mechanism by which it controls migration. Two independent groups have shown direct binding to Rho-family small GTPases: AAMP binds RhoA and suppresses its SMURF2-mediated ubiquitination and degradation, and AAMP interacts with CDC42 and promotes its activation. A third study (PMID:39404373) independently reports that AAMP controls both RhoA and RhoB activity and stability in endothelial cells. On the term choice: GO:0017048 "Rho GTPase binding" is not an available alternative, because it was merged into GO:0031267. QuickGO resolves the identifier GO:0017048 to GO:0031267, which lists it among its secondaryIds alongside GO:0005084, GO:0008536 and GO:0017016, and carries "Rho GTPase binding" as a synonym. There is no live Rho-specific binding term to prefer - GO:0031267 is that term now, and its broader label reflects a deliberate ontology merge rather than a loss of precision. Reason: Supplies the missing molecular function that links AAMP's binding activity to its well-annotated migration and angiogenesis phenotypes. Supporting Evidence: PMID:34901393 AAMP stabilized RhoA by binding to it and suppressing its SMURF2-mediated ubiquitination and degradation. PMID:33279622 AAMP interacted with cell division cycle 42 (CDC42) and promoted its activation, resulting in the formation of cellular protrusions. PMID:39404373 Mechanistically, AAMP controls both RhoA and RhoB activity and stability. |
| GO:0050821 protein stabilization | IMP PMID:34901393 AAMP promotes colorectal cancermetastasis by suppressing SMU... | NEW | Summary: Proposed new annotation capturing the specific mechanism by which AAMP raises active RhoA levels. SMURF2 is an E3 ubiquitin ligase that ubiquitinates RhoA and targets it for degradation; AAMP binds RhoA and suppresses that ubiquitination, so RhoA protein is stabilised and the active pool rises. This is a distinct, mechanistically defined activity rather than a restatement of the binding annotation, and it is what converts AAMP from a Rho-associated protein into a Rho regulator. Reason: Records the demonstrated stabilisation mechanism, which no existing annotation captures. Supporting Evidence: PMID:34901393 AAMP stabilized RhoA by binding to it and suppressing its SMURF2-mediated ubiquitination and degradation. PMID:39404373 Mechanistically, AAMP controls both RhoA and RhoB activity and stability. |
| GO:0051057 positive regulation of small GTPase mediated signal transduction | IMP PMID:26350504 AAMP Regulates Endothelial Cell Migration and Angiogenesis T... | NEW | Summary: Proposed new annotation. AAMP positively regulates Rho-family GTPase signalling, and the effect is directional and consistent across cell types and laboratories: knockdown reduces membrane RhoA activity in smooth muscle cells, RhoA/Rho-kinase signalling mediates AAMP's control of endothelial migration and angiogenesis, AAMP stabilises RhoA against degradation, and AAMP promotes CDC42 activation. GOA currently records the downstream phenotypes (migration, angiogenesis) but not the signalling pathway that produces them. Reason: Connects the two existing process annotations to their shared mechanism; supported by loss-of-function evidence in two cell types from independent groups. Supporting Evidence: PMID:26350504 Furthermore, we identified RhoA/Rho kinase signaling as an important factor that contributes to the action of AAMP in regulating endothelial cell migration and angiogenesis. PMID:18634987 Knockdown of AAMP decreases RhoA activity in the membrane fraction of SMCs. file:human/AAMP/AAMP-deep-research-affinage.md binds CDC42 to promote its activation by impeding the ARHGAP1–CDC42 interaction |
| GO:1903141 negative regulation of establishment of endothelial barrier | IMP PMID:39404373 AAMP and MTSS1 Are Novel Negative Regulators of Endothelial ... | NEW | Summary: Proposed new annotation. A proteomics screen for short-half-life regulators of endothelial integrity identified AAMP, and siRNA depletion of AAMP significantly increased trans-endothelial electrical resistance - that is, loss of AAMP improves barrier function, so AAMP is a negative regulator. The mechanism connects directly to the Rho annotations proposed above: AAMP depletion reduced RhoA and RhoB activity and total RhoA levels, diminishing actomyosin contraction in resting endothelial cells and shifting the spreading/contraction balance toward spreading. This is distinct from the existing migration and angiogenesis terms - barrier function is a separate endothelial property, and GOA records nothing for it. Reason: Adds a distinct, loss-of-function-supported endothelial process that no existing annotation covers, and which shares a mechanism with the proposed Rho-GTPase terms. Supporting Evidence: PMID:39404373 these data identify AAMP and MTSS1 as novel negative regulators of endothelial barrier function PMID:39404373 depletion of AAMP resulted in a significant increase in trans-endothelial electrical resistance |
| GO:0070432 regulation of nucleotide-binding oligomerization domain containing 2 signaling pathway | IMP PMID:19535145 A function for AAMP in Nod2-mediated NF-kappaB activation. | NEW | Summary: Proposed new annotation covering AAMP's innate-immune role, which the gene description reports but which GOA does not represent at all. AAMP was identified as a NOD2 binding partner in a two-hybrid screen, the interaction was confirmed by co-immunoprecipitation from human cells and mapped to an internal peptide spanning three WD40 domains, and both overexpression and siRNA knockdown showed that AAMP modulates NOD2- and NOD1-mediated NF-kappaB activation in HEK293T cells. The non-directional parent term is used deliberately: the paper says "modulates" and does not establish a consistent direction, so GO:0070434 (positive) or GO:0070433 (negative) would assert more than the evidence supports. Bidirectional perturbation in a human cell line is nonetheless IMP-grade evidence for regulation as such. Reason: Represents a documented, experimentally supported arm of AAMP function that GOA omits entirely; the unsigned parent is chosen because the source does not resolve direction. Deliberately not carried into core_functions: it rests on a single 2009 study with no follow-up and is mechanistically disconnected from the Rho-GTPase axis that accounts for everything else this gene does. Annotated because the evidence supports it, kept non-core because its weight relative to the rest of the record is small. Supporting Evidence: PMID:19535145 we showed that AAMP modulates Nod2- and Nod1-mediated NF-kappaB activation in HEK293T cells. PMID:19535145 revealed that an internal peptide of AAMP spanning three WD40 domains was sufficient for this interaction. |
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Download this section (compressed HTML)Q: Should the GO:0014909 IEP annotation be re-coded as IMP? PMID:18634987 reports overexpression, antibody-blockade and siRNA perturbations plus an in vivo antibody experiment in apoE-null mice - direct perturbation evidence, not an expression pattern. The same paper's evidence code also determines what the self-referential IBA on this gene is effectively transferring.
Q: How does AAMP protect RhoA from SMURF2 without being a ubiquitin-pathway protein itself - steric occlusion of the SMURF2 docking site, or competition for the same surface? A structural answer would determine whether a more specific molecular function term, such as a ubiquitin-ligase inhibitor activity, is justified.
Q: Are the cytosolic GTPase-regulating pool and the cell-surface heparin-binding pool the same protein doing two jobs, or is there a targeting mechanism that partitions them? AAMP has no signal peptide, so how the surface pool gets there is unexplained.
Q: Does the AAMP-AEN interaction mean anything? It is the only partner in the GOA record, is reproducible across four screens including an orthogonal AP-MS method, and yet is entirely unconnected to AAMP's characterised biology and has never been followed up.
Q: Is the NOD2/NF-kappaB arm mechanistically independent of the Rho-GTPase arm, or does it also run through cytoskeletal regulation? Rho GTPases are known modulators of NOD signalling, so the two functions may not be as separate as the literature presents them.
Experiment: Map the AAMP-RhoA interface by crosslinking mass spectrometry or structure determination, then test whether interface mutants that retain RhoA binding still block SMURF2-mediated ubiquitination, separating binding from protection.
Hypothesis: AAMP protects RhoA by occluding the SMURF2 interaction surface.
Type: structural biology and biochemistry
Experiment: Compare cells rescued with wild-type AAMP against a variant that cannot reach the surface, or with surface AAMP selectively blocked by antibody, scoring RhoA activity, stress-fibre formation, heparin-sensitive adhesion and tube formation independently.
Hypothesis: The cell-surface and cytosolic pools of AAMP have separable functions.
Type: cell biology
Experiment: Measure the abundance, ubiquitination and activation state of a panel of Rho-family GTPases (RhoA, RhoB, RhoC, CDC42, RAC1) on AAMP knockout and overexpression, to establish the breadth of the stabilisation activity and whether the CDC42 effect is also stability-based.
Hypothesis: AAMP is a general regulator of Rho-family GTPase stability, not only RhoA.
Type: quantitative proteomics
Experiment: Test the interaction by co-immunoprecipitation at endogenous expression levels and by proximity labelling, and check whether AAMP or AEN behaves as a frequent non-specific partner across unrelated baits in the same datasets.
Hypothesis: The AAMP-AEN interaction is a screen artefact rather than biology.
Type: interaction validation
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