Fig. 4. Less PfEMP1 is expressed on the surface of K^– IE. Western blot analysis of whole cell extracts isolated from K⁺ and K^– trophozoite IEs expressing type 41 PfEMP1. Size-fractionated extracts were hybridised with antibodies to either the conserved C-terminus of type 41 PfEMP1 (-ATS), Exp1, aldolase or KAHRP. Fractions were also isolated from trypsin-treated (5 minutes in 100 µg ml^–1) IEs. The mean and range of three densitometry measurements of the -ATS signal are indicated. Equal signal intensities to KAHRP, Exp-1 and aldolase confirm equal loading of protein extracts and the lack of KAHRP expression in K^– IEs. The molecular weights of proteins labelled are indicated (kDa).