Figure 1

Detergent and osmotic lysis extracts of biotinylated P. falciparum PESAs. Panel A. Western blotting of detergent extracts from surface biotinylated P. falciparum infected erythrocytes. Biotinylated proteins were detected by horseradish peroxidase-linked streptavidin. Panel B. Western blotting of surface biotinylated P. falciparum infected erythrocyte extracts prepared by osmotic lysis with biotinylated proteins detected by horseradish peroxidase-linked streptavidin. I/U indicates extracts from P. falciparum infected and uninfected erythrocytes. The first four lanes in panels A, C and E contain Triton X-100 insoluble material (Ti) whereas the succeeding four lanes contain Triton X-100 soluble material (Ts). The first two lanes in panels B, D and F contain the insoluble fractions which can be pelleted by centrifugation after osmotic lysis (Op), the next four lanes contain the post-osmotic lysis membranous fraction (Om) and the final two lanes contain the osmotic lysis supernatant fraction (Os). The solid arrowheads highlight Triton-insoluble, infected erythrocyte-specific, trypsin-sensitive biotinylated proteins. The empty arrowhead highlights a ~110 kDa Triton-soluble, infected erythrocyte-specific, trypsin-sensitive biotinylated protein which also partitions into the osmotic lysis pellet.Panel C and D. Blots A and B respectively, were re-probed with an anti-PfEMP1 antiserum to show co-localization with a biotin-labelled, infected erythrocyte-specific, trypsin-sensitive protein expressed by the R29 parasite clone. Panel E and F. Silver stained duplicate gels of the gels used to prepare the Western blots shown in Panel A and B respectively to confirm the integrity of the protein extracts.