A monoclonal antibody, 1C4, was produced which recognizes a 65 kDa protein that is localized to the plasma membrane of human erythrocytes infected with Plasmodium falciparum. By immunofluorescence the antigen was visualized as dots on the surface of the infected cell. The 65 kDa protein was present in 4 strains of diverse geographical origin, and in erythrocytes infected with a knobless strain. The 65 kDa protein was insoluble in non-ionic detergents, but was partly soluble in SDS and some high (1 M) śalt solutions. The 65 kDa protein is recognized by antibodies specific for the cytoplasmic domain and the N-terminal side of the membrane-spanning region of human band 3, but was not recognized by an antibody specific to the C-terminal side of the membrane-spanning region. The results of treatment of the 65 kDa protein with trypsin and chymotrypsin are consistent with the 65 kDa protein being a truncated and covalently modified band 3 molecule which consists of the first 540 amino acids of human band 3.

Epitope mapping of a murine monoclonal antibody (mAb), 5H12, prepared against live Plasmodium falciparum-intected red blood cells indicated that the epitope consisted of amino acid residues 474–487 of the human anion transport protein, band 3. mAb 5H12 enhanced cytoadherence, but inhibited the CD36-like mediated resetting. A synthetic peptide based on the sequence of the epitope (FSFCETNGLE) blocked both resetting and cytoadherence, suggesting that this amino acid sequence may form the CD36-like receptor. The CD36-like region of band 3 was antigenically distinct from platelet or endothelial CD36.