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Characteristics of membrane protein phosphorylation in Plasmodium berghei-infected mouse erythrocytes
Abstract:
Membrane protein phosphorylation in Plasmodium berghei-infected erythrocytes was studied by incubating intact cells with (32P)orthophosphate and incubating isolated membrane with (gamma-32P)ATP. Phosphorylated proteins were detected by autoradiography after sodium dodecylsulfate (SDS)-polyacrylamide gel electrophoresis or isoelectric focusing followed by gel electrophoresis. New phosphorylated proteins were found in membrane from infected erythrocytes, including a protein with electrophoretic mobility identical to band 5, with Mr 43,000. The molar ratio of phosphate to protein ranged between 0.1 and 0.5. Isoelectric focusing-SDS polyacrylamide gel electrophoresis, peptide mapping, extractability properties, and reduction of susceptibility to DNase I inhibition suggested that this protein is phosphorylated actin. In contrast, spectrin phosphorylation in infected erythrocytes was mostly unchanged.
Insights
Researchers identified new phosphorylated proteins in Plasmodium berghei-infected erythrocytes, including a protein likely representing phosphorylated actin. Spectrin phosphorylation remained largely unchanged in infected cells.
Area of Science:
- Biochemistry
- Cell Biology
- Parasitology
Background:
- Malaria, caused by Plasmodium parasites, severely affects red blood cells.
- Understanding host-pathogen interactions at the molecular level is crucial for developing new therapies.
Purpose of the Study:
- To investigate alterations in membrane protein phosphorylation in erythrocytes infected with Plasmodium berghei.
- To identify specific phosphorylated proteins within the infected erythrocyte membrane.
Main Methods:
- Incubation of intact Plasmodium berghei-infected erythrocytes with (32P)orthophosphate.
- Incubation of isolated erythrocyte membranes with (gamma-32P)ATP.
- Detection of phosphorylated proteins using autoradiography after SDS-polyacrylamide gel electrophoresis and isoelectric focusing-SDS polyacrylamide gel electrophoresis.
Main Results:
- Several novel phosphorylated proteins were identified in the membranes of infected erythrocytes.
- A prominent new phosphoprotein, with Mr 43,000 and electrophoretic mobility similar to band 5, was detected.
- Evidence suggests this protein is phosphorylated actin, based on peptide mapping and extractability.
- Phosphorylation of spectrin in infected erythrocytes showed minimal changes.
Conclusions:
- Plasmodium berghei infection induces significant changes in erythrocyte membrane protein phosphorylation, notably involving actin.
- Phosphorylation of actin may play a role in the structural modifications of infected erythrocytes.
- Spectrin phosphorylation appears less affected by the infection compared to other membrane proteins.