Characterization of a Plasmodium falciparum erythrocyte-binding protein paralogous to EBA-175

A member of a Plasmodium receptor family for erythrocyte invasion was ident ified on chromosome 13 from the Plasmodium falciparum genome sequence of th e Sanger Centre (Cambridge, U.K.). The protein (named BAEBL) has homology t o EBA-175, a P. falciparum receptor that binds specifically to sialic acid and the peptide backbone of glycophorin A on erythrocytes. Both EBA-175 and BAEBL localize to the micronemes, organelles at the invasive ends of the p arasites that contain other members of the family. Like EBA-175. the erythr ocyte receptor for BAEBL is destroyed by neuraminidase and trypsin, indicat ing that the erythrocyte receptor is a sialoglycoprotein. Its specificity, however, differs from that of EBA-175 in that BAEBL can bind to erythrocyte s that lack glycophorin A, the receptor for EBA-175. It has reduced binding to erythrocytes with the Gerbich mutation found in another erythrocyte, si aloglycoprotein (glycophorin C/D). The interest in BAEBL's reduced binding to Gerbich erythrocytes derives from the high frequency of the Gerbich phen otype in some regions of Papua New Guinea where P, falciparum is hyperendem ic.