| 2000 |
GCalpha (PfGCalpha) is a large bifunctional integral membrane protein in P. falciparum whose N-terminal region has strong similarity to P-type ATPases, and whose C-terminal region conforms to the structure of G protein-dependent adenylyl/guanylyl cyclases with two sets of six transmembrane sequences each followed by a catalytic domain (C1 and C2). Key enzymatically important residues are swapped between C1 and C2 relative to mammalian adenylyl cyclases, and certain residues are more characteristic of guanylyl cyclases. GCalpha is expressed in sexual but not asexual blood stages and localizes to the parasite/parasitophorous vacuole membrane region of gametocytes. |
Sequence/structural analysis, immunolocalization; guanylyl cyclase activity confirmed by expression of catalytic domains of the related GCbeta in E. coli (direct enzymatic assay for the family); gene expression analysis across life-cycle stages |
The Journal of biological chemistry |
Medium |
10747978
|
| 2020 |
GCalpha in P. yoelii interacts physically with GEP1, an intracellular membrane protein required for xanthurenic acid (XA)-stimulated cGMP synthesis and gametogenesis. Both GEP1 and GCalpha localize to cytoplasmic puncta in male and female gametocytes. Depletion of GCalpha impairs XA-stimulated gametogenesis, phenocopying GEP1 disruption, including abolishing cGMP synthesis, Ca2+ mobilization, gamete formation, and egress from erythrocytes. |
Co-immunoprecipitation (GEP1-GCalpha interaction), CRISPR/Cas9 gene disruption of GCalpha (loss-of-function with defined cellular phenotype), immunofluorescence localization |
Nature communications |
Medium |
32273496
|
| 2020 |
GCalpha (PfGCalpha) is a functional target of protein phosphatase 1 (PfPP1) in P. falciparum asexual blood stages. Phosphoproteomic and chemical-genetic analysis identified GCalpha as a downstream effector of PfPP1 required for merozoite egress, with the proposed mechanism that PfPP1 regulates lipid sensing by GCalpha; phosphatidylcholine was found to stimulate PfPP1-dependent egress. |
Phosphoproteomic analysis, chemical-genetic (rapamycin-inducible knockdown of PfPP1), lipid stimulation assay |
Nature communications |
Medium |
32669539
|
| 2021 |
GCalpha (PfGCalpha) is the sole enzyme responsible for cGMP synthesis in asexual blood-stage P. falciparum and is essential for merozoite egress from host erythrocytes. GCalpha-null parasites cannot synthesize cGMP or mobilize calcium. Chemical complementation with a cGMP analogue rescued egress, confirming cGMP production as the critical function. Point mutagenesis of a conserved residue in the P4-ATPase domain abolished function, demonstrating that P4-ATPase activity is upstream of and required for cGMP synthesis. |
Conditional gene knockout (GCalpha-null parasites), cGMP measurement, calcium mobilization assay, chemical complementation with cGMP analogue, point mutagenesis of P4-ATPase catalytic residue |
mBio |
High |
33500341
|
| 2022 |
CDC50B is a binding partner of GCalpha in P. falciparum asexual blood stages. CDC50B interacts with GCalpha and modulates the rate of parasite egress by supporting optimal cGMP synthesis. CDC50B is not essential for intraerythrocytic maturation but influences egress efficiency through its interaction with GCalpha. |
Gene tagging, conditional gene disruption, co-immunoprecipitation (CDC50B-GCalpha), cGMP measurement, egress assay |
mBio |
High |
35862778
|
| 2023 |
GCalpha interacts with two multipass membrane cofactors in P. falciparum schizonts and gametocytes: UGO (unique GC organizer) and SLF (signaling linking factor). SLF regulates GCalpha basal activity, while UGO is essential for GCalpha up-regulation in response to natural signals triggering merozoite egress and gametocyte activation. Temperature-dependent epistatic interactions between phosphodiesterases counterbalance GCalpha basal activity, preventing premature gametocyte activation. |
Co-immunoprecipitation (GCalpha-UGO and GCalpha-SLF interactions), conditional gene disruption of UGO and SLF with cGMP/phenotypic readouts, epistasis analysis (temperature-dependent PDE interactions) |
Science advances |
High |
37327340
|
| 2025 |
PP1 phosphatase controls the homeostasis of cGMP in P. falciparum by modulating the basal activity of GCalpha. In PfPP1-null schizonts, the rounding-up of the parasitophorous vacuole (the first step of egress) is almost completely abolished, and this step is Ca2+-dependent. PP1 is placed upstream of the cGMP-PKG signaling pathway, upstream of GCalpha-mediated cGMP production. |
Chemical genetics (conditional PfPP1-iKO line), live-microscopy with fluorescent reporters of vacuole morphology, rescue with cGMP/calcium ionophore A23187 (epistasis via chemical complementation) |
PLoS pathogens |
Medium |
39808636
|
| 2025 |
Phosphoproteomic analysis of P. berghei PP6-null parasites detected increased phosphorylation at Ser508 of GCalpha, indicating that PbPP6 regulates cGMP-PKG-Ca2+ signaling during gametogenesis by modulating GCalpha activity. Loss of PbPP6 resulted in diminished intracellular cGMP levels and decreased cytosolic Ca2+ mobilization in activated gametocytes. |
Phosphoproteomic analysis (Ser508 phosphorylation site on GCalpha), genetic disruption of pbpp6 with cGMP and Ca2+ measurements |
PLoS pathogens |
Medium |
40623036
|
| 2025 |
UA2239, an acyclic nucleoside phosphonate, blocks merozoite and gamete egress in P. falciparum by decreasing cGMP levels, strongly implicating GCalpha as its primary enzymatic target. Resistance mutations arising under drug pressure mapped not to GCalpha itself but to downstream effectors in the cGMP-dependent pathway. |
cGMP level measurements in drug-treated parasites, resistance mutation mapping by whole-genome sequencing, egress inhibition assays |
Science advances |
Medium |
41270172
|