gpaB encodes Gα2 (G alpha-2), the heterotrimeric G-protein alpha subunit of Dictyostelium discoideum that couples the cyclic AMP chemoattractant receptor cAR1 to intracellular signaling during the aggregation stage of development. Like other Gα subunits it binds guanine nucleotides and cycles between an inactive GDP-bound heterotrimeric state (associated with Gβγ) and an active GTP-bound state, functioning as a molecular switch with intrinsic GTPase activity. Gα2 is N-myristoylated on Gly-2 and S-palmitoylated on Cys-4, lipid modifications required for its plasma membrane localization; it also maintains a cytosolic pool that is shuttled to the membrane upon receptor activation. Upon cAMP stimulation, activated Gα2 engages downstream effectors including the Rap1-specific guanine nucleotide exchange factor GflB, thereby linking the GPCR to Ras/Rap signaling at the leading edge, as well as the RasGAP C2GAP1, and it is required for chemoattractant-stimulated phospholipase C activity. Gα2 is essential for cAMP relay, chemotaxis, cell aggregation and the transition to multicellular development, and cells lacking Gα2 fail to enter the developmental phase. Its amino-terminal MAPK docking (D-) motif is required for cAMP-stimulated nucleocytoplasmic shuttling of the GtaC transcription factor during aggregation.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003925 G protein activity | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic (IBA) inference that Gα2 has G protein activity. This is the canonical molecular function of a heterotrimeric Gα subunit and is independently supported by direct experimental evidence in Dictyostelium. Reason: Gα2 is a bona fide heterotrimeric G-protein alpha subunit that acts as a molecular switch (GTPase-driven GDP/GTP cycling). The IBA inference is correct and represents a core function of the gene. Supporting Evidence: PMID:8280098 mutant fgd A, lacking the G-protein alpha-subunit G alpha 2, showed no stimulation by either cAMP...indicating that G alpha 2 is the stimulatory G-protein |
| GO:0005737 cytoplasm | IBA GO_REF:0000033 | ACCEPT | Summary: IBA inference that Gα2 is active in the cytoplasm. Gα2 does maintain a cytosolic pool (sequestered by Gip1) in addition to its membrane pool, so cytoplasmic activity is reasonable, though the primary site of action is the plasma membrane. Reason: A cytosolic pool of the G protein exists and is shuttled to the membrane upon receptor activation, consistent with cytoplasmic localization/activity. Supporting Evidence: PMID:27044073 Gip1 was found to bind and sequester G proteins in cytosolic pools |
| GO:0007188 adenylate cyclase-modulating G protein-coupled receptor signaling pathway | IBA GO_REF:0000033 | ACCEPT | Summary: IBA inference placing Gα2 in cAMP-receptor (adenylate cyclase-modulating) GPCR signaling. This matches the established role of Gα2 as the transducer coupling the cAR1 cAMP receptor during aggregation. Reason: Gα2 is the alpha subunit coupling the cAMP chemoattractant GPCR to downstream effectors during aggregation, a core process. Also supported by a direct-evidence annotation to the same term (PMID:15563608). Supporting Evidence: PMID:34418534 required for chemotaxis to cAMP during the onset of multicellular development |
| GO:0005834 heterotrimeric G-protein complex | IBA GO_REF:0000033 | ACCEPT | Summary: IBA inference of heterotrimeric G-protein complex membership. Directly confirmed in Dictyostelium by FRET between Gα2 and Gβγ subunits. Reason: Gα2 assembles with Gβ and Gγ into a heterotrimer that dissociates on receptor activation; this is a core cellular-component assignment. Supporting Evidence: PMID:11264536 The G-protein heterotrimer rapidly dissociated and reassociated upon addition and removal of chemoattractant |
| GO:0001664 G protein-coupled receptor binding | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO (IEA) inference that Gα2 binds a GPCR. Gα subunits are activated by, and physically couple to, agonist-occupied receptors; this is also supported by a direct-evidence annotation (PMID:11264536). Reason: Receptor-catalyzed nucleotide exchange requires Gα2 engagement with the occupied cAMP receptor, a core aspect of its signaling function. Supporting Evidence: PMID:11264536 occupied receptors, whether or not they are phosphorylated, catalyze the G-protein cycle |
| GO:0003924 GTPase activity | IEA GO_REF:0000120 | ACCEPT | Summary: IEA inference of GTPase activity. The intrinsic GTPase of the Gα subunit is the timer that returns the protein to its inactive GDP-bound state and is intrinsic to G protein switch function. Reason: Gα2 contains the canonical G-alpha GTP-binding/hydrolysis motifs (G1-G5) and functions as a GTPase-driven molecular switch. This is a core molecular function, closely related to the more specific term GO:0003925 (G protein activity). Supporting Evidence: PMID:15715993 The switch mechanism is a function of the inherent GTPase activity of the alpha-subunit |
| GO:0005515 protein binding | IPI PMID:42121920 Heterotrimeric G Protein-RasGAP Coupling Drives Adaptation D... | KEEP AS NON CORE | Summary: IPI protein-binding annotation from the C2GAP1 interaction study. Gα2 directly associates with the RasGAP C2GAP1, preferentially in its activated state, to attenuate Ras signaling during gradient sensing. The bare "protein binding" term is uninformative; the interaction itself is real but not a core molecular function descriptor. Reason: The physical interaction with C2GAP1 is experimentally supported, but GO:0005515 is too generic to represent a core function. Retained as non-core evidence of an effector interaction. Supporting Evidence: PMID:42121920 C2GAP1 directly associates with Gα2 in both GDP- and GTP-bound states, with preferential binding to activated Gα2 |
| GO:0005525 GTP binding | IEA GO_REF:0000002 | ACCEPT | Summary: IEA inference of GTP binding, consistent with the guanine-nucleotide binding site in the G-alpha fold. Also supported by an IC annotation (PMID:8280098) and by numerous conserved GTP-binding residues in UniProt. Reason: GTP binding is intrinsic to Gα2 function as a nucleotide-dependent molecular switch; a core molecular function. Supporting Evidence: PMID:8280098 mutant fgd A, lacking the G-protein alpha-subunit G alpha 2, showed no stimulation by either cAMP |
| GO:0005737 cytoplasm | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA machine-learning (IEA) localization to cytoplasm. Broad and partially redundant with the more specific plasma membrane and cytosol annotations; Gα2 does have a cytosolic pool in addition to its membrane pool. Reason: Correct localization (a cytosolic pool of Gα2 exists), consistent with the IBA cytoplasm annotation, though the functionally important sites are the plasma membrane and the cytosolic reserve pool. Supporting Evidence: PMID:27044073 Gip1 was found to bind and sequester G proteins in cytosolic pools |
| GO:0005834 heterotrimeric G-protein complex | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro2GO (IEA) heterotrimeric complex membership, redundant with and corroborated by direct-evidence annotations (PMID:11264536, PMID:12217653). Reason: Gα2 is a subunit of the heterotrimeric G protein; a core cellular component assignment. Supporting Evidence: PMID:11264536 The G-protein heterotrimer rapidly dissociated and reassociated upon addition and removal of chemoattractant |
| GO:0007010 cytoskeleton organization | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: ARBA (IEA) inference of a broad cytoskeleton-organization role. Gα2 signaling does drive actin cytoskeletal reorganization during chemoattractant-directed migration, but this is an indirect, downstream consequence and the term is very general. Reason: The link to the cytoskeleton is real but indirect (via Ras/Rap and actin dynamics downstream of Gα2) and the generic ARBA term does not represent a core molecular function. Supporting Evidence: PMID:27237792 resulting in defective chemotaxis |
| GO:0007165 signal transduction | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: IEA inference of the generic parent term "signal transduction". Correct but subsumed by the more specific GPCR-signaling annotations. Reason: Accurate but too high-level to be informative; the specific role is in cAMP GPCR signaling captured by GO:0007186/GO:0007188. Supporting Evidence: PMID:15715993 act as molecular switches to relay information from transmembrane receptors to intracellular effectors |
| GO:0007186 G protein-coupled receptor signaling pathway | IEA GO_REF:0000002 | ACCEPT | Summary: IEA inference placing Gα2 in GPCR signaling. This is the defining process for a heterotrimeric Gα subunit coupling the cAMP receptor cAR1. Reason: GPCR signaling is a core biological process for Gα2; well supported by the experimental literature on cAMP receptor coupling. Supporting Evidence: PMID:34418534 required for chemotaxis to cAMP during the onset of multicellular development |
| GO:0019001 guanyl nucleotide binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: IEA inference of guanyl nucleotide binding, the parent of GTP binding. Correct but redundant with the more specific GO:0005525 (GTP binding). Reason: Accurate but non-specific; the informative term is GTP binding. Supporting Evidence: PMID:8280098 mutant fgd A, lacking the G-protein alpha-subunit G alpha 2, showed no stimulation by either cAMP |
| GO:0031683 G-protein beta/gamma-subunit complex binding | IEA GO_REF:0000002 | ACCEPT | Summary: IEA inference that Gα2 binds the Gβγ dimer. This is intrinsic to heterotrimer assembly and is directly demonstrated by Gα2/Gβγ FRET and by the beta-subunit binding annotation (PMID:15563608). Reason: Association with Gβγ is a defining property of the Gα subunit; core molecular function related to complex assembly. Supporting Evidence: PMID:15563608 triggers dissociation of Galpha and Gbetagamma subunits |
| GO:1904776 regulation of protein localization to cell cortex | IMP PMID:40934557 The Ras association domain of DydA as a specific reporter of... | KEEP AS NON CORE | Summary: IMP annotation from the DydA RasG-reporter study, where cortical/leading-edge localization of the activated-RasG biosensor required GPCR (Car1/3) and G-protein signaling. This places Gα2 upstream of the cortical recruitment of a downstream Ras effector. Reason: The effect on cortical protein localization is an indirect, downstream consequence of Gα2-initiated chemoattractant signaling rather than a core molecular function. Supporting Evidence: PMID:40934557 This localization required GPCR Car1/3 and G-protein signaling |
| GO:0007264 small GTPase-mediated signal transduction | IMP PMID:8280098 Phospholipase C in Dictyostelium discoideum. Identification ... | UNDECIDED | Summary: IMP annotation to small GTPase-mediated signal transduction citing the phospholipase C study. Gα2 is a heterotrimeric (not small) GTPase, and the cited paper concerns cAMP/GTP-analog regulation of phospholipase C rather than small GTPase signaling per se. The cached content does not establish this specific term, and I cannot verify the curator's full-text basis. Reason: The cited reference (abstract available) addresses G alpha 2 as the stimulatory G protein for phospholipase C, not small GTPase-mediated signal transduction. Although Gα2 does act upstream of Ras/Rap small GTPases in other studies, the term-to-reference support here cannot be confirmed, so per policy this is left UNDECIDED rather than removed. |
| GO:0005091 guanyl-nucleotide exchange factor adaptor activity | IDA PMID:27237792 A Gα-Stimulated RapGEF Is a Receptor-Proximal Regulator of D... | ACCEPT | Summary: Direct-evidence annotation: activated Gα2 binds and stimulates the Rap1-specific GEF GflB, directly coupling the cAMP GPCR to Rap1. Gα2 thus acts as a Gα-stimulated GEF adaptor for monomeric G-protein signaling. Reason: This captures a well-supported, receptor-proximal core molecular function of Gα2 as an effector-activating adaptor at the leading edge. Supporting Evidence: PMID:27237792 we identify GflB, a Gα2 binding partner that directly couples the Dictyostelium cyclic AMP GPCR to Rap1 PMID:27237792 functions as a Gα-stimulated, Rap1-specific guanine nucleotide exchange factor |
| GO:0030695 GTPase regulator activity | IDA PMID:21103944 Chemoattractant-mediated Rap1 activation requires GPCR/G pro... | KEEP AS NON CORE | Summary: IDA annotation reflecting that chemoattractant-stimulated activation of the small GTPase Rap1 requires Gα2. Gα2 regulates Rap1 activation state (via GflB), consistent with GTPase regulator activity. Reason: Correct but generic; the more precise mechanistic function is the GflB-stimulating GEF-adaptor activity (GO:0005091). Retained as non-core. Supporting Evidence: PMID:21103944 was absent in cells lacking chemoattractant cAMP receptors cAR1/cAR3 or a subunit of the heterotrimeric G-protein complex Gα2 |
| GO:0009617 response to bacterium | IDA PMID:35544746 Soil Amoebae Affect Iron and Chromium Reduction through Pref... | UNDECIDED | Summary: IDA annotation citing an environmental-microbiology study of Dictyostelium predation on metal-reducing bacteria. The cached abstract does not mention Gα2/gpaB, and I cannot verify a specific role for Gα2 in this response from the available text. Reason: Per policy, an experimental annotation whose supporting publication I cannot verify (abstract-only, no mention of the gene) is left UNDECIDED rather than removed. |
| GO:0005886 plasma membrane | IDA PMID:27044073 Heterotrimeric G-protein shuttling via Gip1 extends the dyna... | ACCEPT | Summary: Direct-evidence plasma membrane localization/activity. Receptor activation recruits the G protein to the plasma membrane from the cytosol (Gip1 shuttling), the site where Gα2 signaling occurs. Reason: The plasma membrane is the principal site of Gα2 action; well supported by the shuttling data and by palmitoylation-dependent membrane targeting. Supporting Evidence: PMID:27044073 Receptor activation induced G-protein translocation to the plasma membrane from the cytosol in a Gip1-dependent manner |
| GO:0006355 regulation of DNA-templated transcription | IMP PMID:34418534 MAPK docking motif in the Dictyostelium Gα2 subunit is requi... | KEEP AS NON CORE | Summary: IMP annotation from the MAPK docking-motif study. The Gα2 D-motif is required for cAMP-stimulated nucleocytoplasmic shuttling of the GtaC transcription factor, a process linked to gene regulation during aggregation. Gα2 thus influences transcription indirectly via control of GtaC. Reason: The transcriptional effect is indirect (mediated through GtaC localization) rather than a direct/core molecular function of Gα2. Supporting Evidence: PMID:34418534 shuttling of GtaC is thought to be an important process for gene regulation during the aggregation phase of development PMID:34418534 Expression of the Gα2 subunit but not the Gα2D− subunit fully restored the ability of cAMP to stimulate the translocation of the GtaC transcription factor |
| GO:0046825 regulation of protein export from nucleus | IMP PMID:34418534 MAPK docking motif in the Dictyostelium Gα2 subunit is requi... | KEEP AS NON CORE | Summary: IMP annotation reflecting the requirement of the Gα2 D-motif for cAMP-stimulated movement of the GtaC transcription factor from the nucleus to the cytoplasm. Reason: Gα2 regulates GtaC nuclear export indirectly through its signaling and docking-motif function; a downstream, non-core role. Supporting Evidence: PMID:34418534 movement of GtaC from the nucleus to the cytoplasm |
| GO:0005829 cytosol | IDA PMID:27044073 Heterotrimeric G-protein shuttling via Gip1 extends the dyna... | ACCEPT | Summary: Direct-evidence cytosolic localization: a pool of the heterotrimeric G protein is sequestered in the cytosol by Gip1 and shuttled to the membrane upon receptor activation. Reason: A defined cytosolic reserve pool of Gα2 exists and is functionally important for extending the dynamic range of chemotaxis. Supporting Evidence: PMID:27044073 Gip1 was found to bind and sequester G proteins in cytosolic pools |
| GO:0005886 plasma membrane | IDA PMID:11264536 Receptor-mediated activation of heterotrimeric G-proteins in... | ACCEPT | Summary: Direct-evidence plasma membrane localization/activity consistent with the FRET studies of receptor-mediated G-protein activation at the cell surface and with palmitoylation-dependent membrane targeting. Reason: The plasma membrane is the principal site of Gα2 signaling; corroborated across multiple studies. Supporting Evidence: PMID:29352733 plasma membrane localization |
| GO:0031681 G-protein beta-subunit binding | IDA PMID:15563608 Quantitative imaging of single live cells reveals spatiotemp... | ACCEPT | Summary: Direct-evidence binding to the G-protein beta subunit, demonstrated by Gα/Gβγ FRET showing receptor-triggered dissociation and reassociation of the subunits. Reason: Association with the Gβ(γ) subunit is a defining, core property of Gα2 within the heterotrimer. Supporting Evidence: PMID:15563608 triggers dissociation of Galpha and Gbetagamma subunits |
| GO:0005829 cytosol | IDA PMID:11264536 Receptor-mediated activation of heterotrimeric G-proteins in... | ACCEPT | Summary: Direct-evidence cytosolic localization, consistent with the cytosolic pool of heterotrimeric G protein described in Dictyostelium. Reason: Gα2 has a documented cytosolic pool in addition to its membrane pool. Supporting Evidence: PMID:27044073 Gip1 was found to bind and sequester G proteins in cytosolic pools |
| GO:0005525 GTP binding | IC PMID:8280098 Phospholipase C in Dictyostelium discoideum. Identification ... | ACCEPT | Summary: Curator-inferred (IC) GTP binding, consistent with the GTP-analog-dependent stimulation of phospholipase C through Gα2 and the conserved guanine-nucleotide-binding fold. Reason: GTP binding is an intrinsic, core molecular function of the Gα2 subunit. Supporting Evidence: PMID:8280098 mutant fgd A, lacking the G-protein alpha-subunit G alpha 2, showed no stimulation by either cAMP...indicating that G alpha 2 is the stimulatory G-protein |
| GO:0003925 G protein activity | IMP PMID:8280098 Phospholipase C in Dictyostelium discoideum. Identification ... | ACCEPT | Summary: IMP annotation: loss of Gα2 (mutant fgd A) abolishes cAMP- and GTP-analog-stimulated phospholipase C activity, identifying Gα2 as the functional stimulatory G protein. Direct genetic support for G protein activity. Reason: This is core molecular-function evidence: the Gα2-null phenotype demonstrates that Gα2 provides the stimulatory G protein activity coupling the cAMP receptor to phospholipase C. Supporting Evidence: PMID:8280098 mutant fgd A, lacking the G-protein alpha-subunit G alpha 2, showed no stimulation by either cAMP...indicating that G alpha 2 is the stimulatory G-protein |
| GO:0001664 G protein-coupled receptor binding | IDA PMID:11264536 Receptor-mediated activation of heterotrimeric G-proteins in... | ACCEPT | Summary: Direct-evidence GPCR binding: in living cells, occupied cAMP receptors catalyze the Gα2 G-protein cycle, demonstrating functional coupling of Gα2 to the receptor. Reason: Physical/functional coupling to the occupied cAMP receptor is a core aspect of Gα2 activation. Supporting Evidence: PMID:11264536 occupied receptors, whether or not they are phosphorylated, catalyze the G-protein cycle |
| GO:0005515 protein binding | IPI PMID:15563608 Quantitative imaging of single live cells reveals spatiotemp... | KEEP AS NON CORE | Summary: Generic IPI protein-binding annotation from the FRET study; the meaningful interaction (with the Gβγ subunit) is better captured by GO:0031681 (G-protein beta-subunit binding) annotated from the same paper. Reason: GO:0005515 is uninformative; the specific interaction is already recorded as beta-subunit binding. Retained as non-core. Supporting Evidence: PMID:15563608 triggers dissociation of Galpha and Gbetagamma subunits |
| GO:0005515 protein binding | IPI PMID:23576747 Dictyostelium Ric8 is a nonreceptor guanine exchange factor ... | KEEP AS NON CORE | Summary: IPI protein-binding annotation from the Ric8 study. Gα proteins were used as bait to identify Ric8 as a nonreceptor GEF for Gα, evidencing a physical Gα2-Ric8 interaction. The bare term is uninformative. Reason: The Ric8 interaction is experimentally supported but GO:0005515 is too generic to be a core function descriptor; retained as non-core. Supporting Evidence: PMID:23576747 nonreceptor guanine nucleotide exchange factor for Gα-protein |
| GO:0005515 protein binding | IPI PMID:24349132 A RabGAP regulates life-cycle duration via trimeric G-protei... | KEEP AS NON CORE | Summary: IPI protein-binding annotation reflecting the interaction between the RabGAP Dd Rbg-3 and Gα subunits (including Gα2) in an activity-dependent manner. Bare "protein binding" is uninformative. Reason: The Dd Rbg-3 interaction is supported but the generic term is not a core function; retained as non-core. Supporting Evidence: PMID:24349132 Dd Rbg-3 interacts with 2 Gα subunits in an activity-dependent manner in vitro |
| GO:0005515 protein binding | IPI PMID:24930026 The Dictyostelium discoideum RACK1 orthologue has roles in g... | KEEP AS NON CORE | Summary: IPI protein-binding annotation from the DdRACK1 (gpbB) study, which shows DdRACK1 interacts with G-protein alpha, beta and gamma subunits by yeast two-hybrid, pulldown and immunoprecipitation. Bare term is uninformative. Reason: The DdRACK1 interaction is supported but GO:0005515 is too generic for a core function; retained as non-core. Supporting Evidence: PMID:24930026 DdRACK1 interacts with G protein subunits alpha, beta and gamma as shown by yeast two-hybrid, pulldown, and immunoprecipitation assays |
| GO:0005515 protein binding | IPI PMID:27044073 Heterotrimeric G-protein shuttling via Gip1 extends the dyna... | KEEP AS NON CORE | Summary: IPI protein-binding annotation reflecting the Gip1-G protein interaction, by which Gip1 binds and sequesters the heterotrimeric G protein in the cytosol. Bare term is uninformative. Reason: The Gip1 interaction is supported but the generic term does not represent a core function; retained as non-core. Supporting Evidence: PMID:27044073 Gip1 was found to bind and sequester G proteins in cytosolic pools |
| GO:0005515 protein binding | IPI PMID:27237792 A Gα-Stimulated RapGEF Is a Receptor-Proximal Regulator of D... | KEEP AS NON CORE | Summary: IPI protein-binding annotation for the Gα2-GflB interaction. This interaction is functionally captured by the GEF-adaptor activity annotation (GO:0005091) from the same study; the bare term is uninformative on its own. Reason: The GflB interaction is core to Gα2 signaling but is better represented by GO:0005091; GO:0005515 itself is retained as non-core. Supporting Evidence: PMID:27237792 we identify GflB, a Gα2 binding partner that directly couples the Dictyostelium cyclic AMP GPCR to Rap1 |
| GO:0005834 heterotrimeric G-protein complex | IDA PMID:11264536 Receptor-mediated activation of heterotrimeric G-proteins in... | ACCEPT | Summary: Direct-evidence heterotrimeric complex membership: FRET between Gα2 and Gβγ demonstrates the assembled heterotrimer dissociating and reassociating with receptor activation. Reason: Core cellular-component assignment, directly demonstrated in living cells. Supporting Evidence: PMID:11264536 The G-protein heterotrimer rapidly dissociated and reassociated upon addition and removal of chemoattractant |
| GO:0005834 heterotrimeric G-protein complex | IDA PMID:12217653 Monitoring receptor-mediated activation of heterotrimeric G-... | ACCEPT | Summary: Direct-evidence heterotrimeric complex membership from the FRET methodology paper, in which Galpha2 and Gbetagamma were tagged to monitor the state of the G-protein heterotrimer. Reason: Corroborates the core heterotrimeric-complex assignment for Gα2. Supporting Evidence: PMID:12217653 The Galpha(2)and Gbetagamma proteins were tagged with cyan and yellow fluorescent proteins and used to observe the state of the G-protein heterotrimer |
| GO:0005886 plasma membrane | IDA PMID:29352733 Localization of palmitoylated and activated G protein α-subu... | ACCEPT | Summary: Direct-evidence plasma membrane localization. Gα2 is palmitoylated on Cys-4, and loss of this palmitoylation site redistributes Gα2 within the cell, establishing palmitoylation-dependent plasma membrane targeting. Reason: The plasma membrane is the principal functional site of Gα2, dependent on its lipid modifications; a core localization. Supporting Evidence: PMID:29352733 Loss of this palmitoylation site results in redistribution of Gα2 within the cell PMID:29352733 plasma membrane localization |
| GO:0007189 adenylate cyclase-activating G protein-coupled receptor signaling pathway | IMP PMID:15715993 Loss-of-function mutations identified in the Helical domain ... | KEEP AS NON CORE | Summary: IMP annotation from the loss-of-function mutant screen. Gα2 is essential for the cAMP-driven aggregation program; loss of Gα2 blocks entry into development. The specific "adenylate cyclase-activating" wording is a curator interpretation of the cAMP-relay role. Reason: Gα2 is required for the aggregation-stage cAMP signaling program, but adenylate cyclase activation in Dictyostelium is classically driven by Gβγ; the core Gα2 processes are better captured by chemotaxis, aggregation, and adenylate cyclase-modulating GPCR signaling. Retained as non-core. Supporting Evidence: PMID:15715993 G alpha2 is essential for the developmental life cycle of Dictyostelium |
| GO:0006909 phagocytosis | IMP PMID:9647646 G protein beta subunit-null mutants are impaired in phagocyt... | REMOVE | Summary: IMP annotation citing the Gβ-null study. That paper explicitly reports that single Gα-subunit nulls, specifically Gα2 (and Gα4), do NOT show reduced phagocytosis; the phagocytosis defect is a property of the shared Gβ subunit, not Gα2. The annotation is therefore contradicted by its own cited reference. Reason: The cited reference directly states that Gα2-null mutants are not impaired in phagocytosis, so attributing phagocytosis to Gα2 is not supported and is contradicted by the evidence. Phagocytosis in this context depends on Gβ, not the aggregation-stage Gα2. Supporting Evidence: PMID:9647646 nor did we find reduced phagocytosis rates in Gα2 and Gα4 null mutants |
| GO:0030041 actin filament polymerization | IMP PMID:9647646 G protein beta subunit-null mutants are impaired in phagocyt... | KEEP AS NON CORE | Summary: IMP annotation citing the Gβ-null study, whose actin-polymerization phenotypes were characterized in Gβ-null cells. Chemoattractant (cAMP)-induced actin responses do require Gα2 upstream, so Gα2 can be considered upstream of actin polymerization during chemotaxis, but this is an indirect, downstream role. Reason: Gα2 signaling drives actin remodeling during chemoattractant-directed migration, but actin filament polymerization is a downstream cytoskeletal output rather than a core molecular function of Gα2. Supporting Evidence: PMID:9647646 signaling through heterotrimeric G proteins is required for regulating the actin cytoskeleton during phagocytic uptake, as previously shown for chemotaxis |
| GO:0006935 chemotaxis | IMP PMID:15715993 Loss-of-function mutations identified in the Helical domain ... | ACCEPT | Summary: IMP annotation: Gα2 is required for chemotaxis to cAMP at the onset of multicellular development, and loss-of-function Gα2 mutations block the developmental/aggregation program. Reason: Chemotaxis toward cAMP is a core biological process mediated by Gα2 and is strongly supported by the genetics. Supporting Evidence: PMID:34418534 required for chemotaxis to cAMP during the onset of multicellular development PMID:15715993 the loss of G alpha2 function results in a |
| GO:0031152 aggregation involved in sorocarp development | IMP PMID:15715993 Loss-of-function mutations identified in the Helical domain ... | ACCEPT | Summary: IMP annotation: Gα2 is essential for aggregation and the developmental life cycle; loss of Gα2 causes failure of cells to enter the developmental phase. This is the defining Gα2-null phenotype. Reason: Aggregation during sorocarp (fruiting body) development is a core biological process for Gα2, essential and well established. Supporting Evidence: PMID:15715993 G alpha2 is essential for the developmental life cycle of Dictyostelium PMID:34418534 The Dictyostelium Gα2 G protein subunit is required for chemotaxis to cAMP during the onset of multicellular development |
| GO:0007188 adenylate cyclase-modulating G protein-coupled receptor signaling pathway | IDA PMID:15563608 Quantitative imaging of single live cells reveals spatiotemp... | ACCEPT | Summary: Direct-evidence involvement in cAMP GPCR (adenylate cyclase-modulating) signaling, from the quantitative single-cell imaging of chemoattractant receptor activation and G-protein dynamics. Reason: Gα2 transduces cAMP GPCR signaling during gradient sensing, a core process. Supporting Evidence: PMID:15563608 triggers dissociation of Galpha and Gbetagamma subunits |
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)