Analysis of membrane proteins by two-dimensional electrophoresis: Comparison of the proteins extracted from normal or Plasmodium falciparum - infected erythrocyte ghosts

Parasite-encoded membrane proteins translocated to the surface of infected erythrocytes or in specialized vesicles underneath (Maurer's clefts) play a key role in the asexual life cycle of Plasmodium falciparum (a malaria-cau sing protozoan), by mediating key steps such as red blood cell invasion, se questration of infected cells in microcapillaries, and red blood cell ruptu re. A large-scale analysis of these membrane proteins would therefore be of great help to gain knowledge of the different stages of the Plasmodium fal ciparum life cycle. In order to be able to detect and identify parasite-enc oded proteins directed to the red blood cell membrane, we first defined the conditions required for optimal extraction and separation of normal red bl ood cell ghost proteins by two-dimensional gel electrophoresis. These condi tions included the use of urea, thiourea and new zwitterionic detergents in the extraction and isoelectric focusing media. The optimized conditions we re then applied to analyze normal and P. falciparum-infected red blood cell ghosts. Several protein spots were found only in infected ghosts and are e xpected to represent parasite-encoded proteins. These proteins are currentl y under investigation.