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Pit2 assemblies at the cell surface are modulated by extracellular inorganic phosphate concentration
Christine Salaün1, Emmanuel Gyan, Pierre Rodrigues
1Unité Rétrovirus et Transfert Génétique, CNRS URA 1930, Institut Pasteur, 75724 Paris, France.
Journal of Virology
|April 5, 2002
Summary
Pit2, a phosphate transporter and virus receptor, forms cell surface assemblies. These assemblies change shape based on phosphate levels, affecting virus infection and phosphate uptake.
Area of Science:
- Cell biology
- Virology
- Biochemistry
Background:
- Pit2 functions as both a phosphate transporter and a receptor for amphotropic murine leukemia virus.
- Retrovirus receptor assembly is indirectly implicated in triggering membrane fusion.
Purpose of the Study:
- To investigate the formation and dynamics of Pit2 assemblies at the cell surface.
- To determine if Pit2 assembly is influenced by extracellular inorganic phosphate concentration ([P(i)]).
Main Methods:
- Utilized Chinese Hamster Ovary (CHO) cells expressing functional human Pit2 fused to epitope tags.
- Employed cross-linking reagents and trifluoroacetic acid (TFA) treatment to study protein interactions.
- Co-immunoprecipitation was used to detect Pit2 homo-oligomers.
- Assessed assembly presence and detergent resistance.
Main Results:
- Provided evidence that Pit2 forms assemblies at the cell surface, independent of cross-linking or TFA treatment.
- Demonstrated Pit2 homo-oligomer formation.
- Showed that the amount of Pit2 assemblies varies with extracellular inorganic phosphate concentration ([P(i)]) in a twofold range.
- Observed these variations at the cell surface without de novo protein synthesis.
Conclusions:
- Pit2 assemblies exhibit variable conformations at the cell surface in response to extracellular [P(i)].
- A model is proposed where Pit2 assemblies transition between compacted and expanded states.
- These conformational changes may relate to observed variations in phosphate uptake and virus infection susceptibility.