| 2000 |
SBP1 (PF3D7_0501300) is an integral membrane protein of Maurer's clefts. Its carboxy-terminal domain, exposed in the erythrocyte cytoplasm, interacts with a 35 kDa erythrocyte skeletal protein, suggesting SBP1 participates in anchoring Maurer's clefts to the erythrocyte submembrane skeleton. |
Immunoprecipitation with hyperimmune sera, subcellular fractionation, immunofluorescence/immunoelectron microscopy, domain analysis |
Molecular and biochemical parasitology |
Medium |
11087921
|
| 2006 |
Targeted gene disruption of SBP1 in P. falciparum prevents PfEMP1 from reaching the infected red blood cell surface, abolishing IRBC adhesion. PfEMP1 remains in Maurer's clefts and other Maurer's cleft proteins are unaffected, but Maurer's clefts no longer localize close to the cell periphery. Complementation with sbp1 restores PfEMP1 surface expression and adhesion, demonstrating SBP1 is essential for PfEMP1 translocation to the IRBC surface. |
Targeted gene disruption, complementation, immunofluorescence microscopy, cytoadherence assays |
The Journal of cell biology |
High |
16520384
|
| 2006 |
SBP1 functions at the parasitophorous vacuole membrane to load PfEMP1 into Maurer's clefts during their formation. In the absence of SBP1, PfEMP1 fails to reach the IRBC surface and the dominant antibody response of malaria-exposed women to the IRBC surface is abolished. |
Gene disruption, live-cell imaging, immunofluorescence, antibody reactivity assays |
Blood |
High |
17023587
|
| 2006 |
Parasite protein phosphatase 1 (PP1) modulates the phosphorylation status of the amino-terminal domain of SBP1 within the lumen of Maurer's clefts, as shown by co-immunoprecipitation and inhibition studies. Hyperphosphorylation of SBP1 induced by a PP1 inhibitor (calyculin A) prevents merozoite release from the host cell, implicating PP1-mediated SBP1 phosphorylation in red blood cell rupture. |
Co-immunoprecipitation, pharmacological inhibition (calyculin A), phosphorylation assays |
Cellular microbiology |
Medium |
16548885
|
| 2005 |
The C-terminal cytoplasmic domain of SBP1 interacts with the human erythrocyte protein LANCL1, which is specifically recruited to the surface of Maurer's clefts in mature P. falciparum blood stages. This interaction was identified by co-immunoprecipitation and proposed to prevent premature rupture of the red blood cell. |
Co-immunoprecipitation, immunofluorescence microscopy, mass spectrometry identification of LANCL1 |
Molecular and biochemical parasitology |
Medium |
15811525
|
| 2008 |
The transmembrane domain of SBP1 functions as an internal signal sequence for entry into the parasite's secretory pathway and transport to the parasite plasma membrane. Additional N-terminal domains, characterized by high negative net charge, are required for trafficking beyond the parasite plasma membrane to the Maurer's clefts; these domains affect protein solubility, membrane orientation, and subcellular localization. |
Domain deletion/mutation analysis, biochemical fractionation, immunofluorescence microscopy, topology assays |
Traffic (Copenhagen, Denmark) |
Medium |
19054387
|
| 2008 |
The N-terminal region and transmembrane domain of SBP1 can functionally replace the corresponding regions of the unrelated PEXEL-negative exported protein REX2 to direct export, demonstrating that these sequence features are shared among PEXEL-negative exported proteins and are sufficient for export when combined. |
Domain-swap chimera constructs, live-cell fluorescence microscopy, export assays |
Molecular microbiology |
Medium |
19170882
|
| 2008 |
During conditional export experiments, SBP1 physically interacts with the molecular chaperone PfBiP during early export steps, before reaching the Maurer's clefts. |
Conditional aggregation domain (CAD) export system, co-immunoprecipitation, immunofluorescence |
Cellular microbiology |
Low |
18691247
|
| 2013 |
Plasmepsin V does not cleave the N-terminal sequence of SBP1, demonstrating that SBP1 is exported via a PEXEL/Plasmepsin V-independent pathway. |
In vitro Plasmepsin V cleavage assays, N-terminal sequencing |
Traffic (Copenhagen, Denmark) |
Medium |
23387285
|
| 2015 |
The C-terminal cytoplasmic domain of SBP1 binds directly and specifically to defined sub-domains of two major RBC membrane skeleton components, protein 4.1R and spectrin. These interactions serve as a mechanism to anchor Maurer's clefts to the RBC membrane skeleton. However, these interactions alone are necessary but not sufficient for PfEMP1 translocation to the RBC surface; the N-terminal lumenal domain of SBP1 also plays an essential but uncharacterized role. |
Recombinant protein pulldown, binding domain mapping, complementary loss-of-function analysis |
Biochimica et biophysica acta |
Medium |
25883090
|
| 2015 |
SBP1 is exported to the Maurer's clefts as a soluble form in the red cell cytoplasm in association with the parasite group II chaperonin PfTRiC. The domain of interaction with PfTRiC resides within the amino-terminal domain of SBP1. This pathway appears to be shared among multiple Maurer's cleft membrane proteins with different export motifs. |
Co-immunoprecipitation, domain mapping, immunofluorescence microscopy |
Traffic (Copenhagen, Denmark) |
Medium |
25615740
|
| 2016 |
P. berghei orthologues of SBP1 and MAHRP1 are required for CD36-mediated adhesion of P. berghei-infected RBCs to endothelium and for sequestration and virulence in mice. Complementation of P. berghei SBP1 KO with P. falciparum SBP1 restores sequestration and virulence, demonstrating functional conservation of SBP1 between rodent and human malaria parasites. |
Gene knockout, complementation with P. falciparum orthologue, bioluminescence imaging, in vivo adhesion/sequestration assays |
Nature communications |
High |
27225796
|
| 2016 |
Genetic deletion of SBP1 leads to a dramatic reduction in antibody recognition of infected erythrocytes and in opsonic phagocytosis of IEs by human antibodies. The great majority of antibody epitopes on the IE surface are SBP1-dependent, establishing SBP1 as a critical component of the trafficking pathway for major surface antigens targeted by human immunity. |
Targeted gene deletion, flow cytometry, opsonic phagocytosis assays, multi-population antibody studies |
Cellular and molecular life sciences : CMLS |
High |
27193441
|
| 2016 |
P. knowlesi SBP1 (PkSBP1) localizes to membranous structures analogous to Maurer's clefts (Sinton and Mulligan stipplings) in both monkey and human erythrocytes infected with P. knowlesi. When expressed in P. falciparum-infected erythrocytes, recombinant PkSBP1 co-localizes with PfSBP1 at Maurer's clefts, indicating conserved trafficking. |
Epitope-tagged transgenic parasites, immunofluorescence assay, immunoelectron microscopy |
PloS one |
Medium |
27732628
|
| 2019 |
A comprehensive SBP1 interactome was mapped using sensitive proteomics approaches in P. falciparum-infected erythrocytes, identifying numerous exported parasite proteins and host-parasite interactions associated with SBP1 intracellular trafficking and virulence, including MAL8P1.4 as a linked virulence factor. |
Proximity-based/affinity proteomics (co-IP + mass spectrometry), functional validation of interactors |
iScience |
Medium |
31476617
|
| 2019 |
At the early trophozoite (ring form) stage, SBP1 accumulates within electron-dense material (EDM) in the parasite cytoplasm and in the parasitophorous vacuolar space, before being transported to Maurer's clefts in the erythrocyte cytoplasm. This defines EDM as an intermediate compartment in SBP1's export pathway. |
Immunoelectron microscopy with specific anti-SBP1 antibodies |
Parasitology international |
Medium |
31669509
|
| 2017 |
Two PHISTc subfamily proteins (PFD1140w and PF11_0503) interact with SBP1 in vitro. PFD1140w interacts simultaneously with both PfEMP1 (cytoplasmic tail) and SBP1 to form a tripartite complex in vitro. |
Recombinant protein pulldown, co-immunoprecipitation, in vitro binding assay |
The FEBS journal |
Low |
29155505
|
| 2018 |
PfJ23, a PEXEL-positive hyp16 family member, directly interacts with purified SBP1 and both co-localize in parasites. PfEMP1 cytoplasmic tail, PfJ23, and SBP1 can form a complex in vitro, suggesting PfJ23 may assist in export of PEXEL-negative proteins including SBP1. |
Recombinant protein pulldown, in vitro co-immunoprecipitation, co-localization by immunofluorescence |
Pathogens and disease |
Low |
30576479
|
| 2019 |
The cytoplasmic domain of CBP2 (a 2TM exported protein) interacts in vitro with SBP1; this interaction is influenced by ATP binding of CBP2. |
In vitro recombinant protein binding assay |
International journal of biological macromolecules |
Low |
31356937
|
| 2023 |
Using time-resolved proximity biotinylation (SBP1 fused to TurboID), two membrane-associated proteins were identified as pre-export (early) interactors of SBP1 at the parasite plasma membrane, one with a predicted translocon domain. Conditional knockdown of these candidates showed they are essential for asexual growth and localize to the host-parasite interface during early intraerythrocytic stages, suggesting a role in extracting membrane proteins from the parasite plasma membrane for export. |
TurboID proximity biotinylation, label-free quantitative proteomics, conditional knockdown, immunofluorescence |
Journal of cell science |
Medium |
37772444
|
| 2023 |
SBP1 and MAHRP2, despite containing transmembrane segment-like hydrophobic sequences, assume a lumenal topology within the parasite secretory pathway (ER lumen) as a productive intermediate for protein export. Addition of a C-terminal ER-retention signal enhances but does not completely block retention of SBP1 in the parasite ER, indicating a sub-population adopts an ER-lumenal state during the export process. |
Epitope-tagged constructs, ER-retention signal fusion, immunofluorescence, biochemical topology assays in intact cells |
PLoS pathogens |
Medium |
37000891
|
| 2024 |
SBP1 localizes to dot-like Maurer's cleft structures in the cytoplasm of gametocyte-infected erythrocytes (not only asexual stages). Co-immunoprecipitation and mass spectrometry show that SBP1 interacts with the molecular chaperones PfHSP70-1 and PfHSP70-x during gametocyte maturation. |
Immunofluorescence microscopy, co-immunoprecipitation, mass spectrometry |
Parasitology international |
Medium |
38331312
|