Methionine 156 in the immunodominant domain of CD36 contributes to define the epitope recognized by the NL07 MoAb

CD36 is a membrane glycoprotein expressed by several cell types, and play a role as a receptor for different physiological and pathological ligands. A n immunodominant domain of CD36 has been described in the amino acidic regi on 155-183, where many ligands and monoclonal antibodies (MoAbs) react. MoA bs against CD36 have proved useful in structural as well as functional stud ies. One of these antibodies, MoAb NL07, recognizes a conformational epitop e that is acquired in the late steps of the CD36 maturation. The NL07 epito pe appears to be functionally relevant and blocks CD36-mediated binding to red blood cells infected with the malaria parasite Plasmodium falciparum (I RBC). In this work a mutant COS-7 clone expressing NL07-negative CD36 molec ules on the cell surface was investigated. In the mutant, the methionine in position 156 of the wild type CD36 sequence was replaced by a valine. It w as determined that methionine 156 was essential for NL07 reactivity, mappin g the NL07 epitope to the vicinity of the functionally important immunodomi nant domain (aa 155-183) of CD36. Although methionine 156 is located in thi s region, the CD36V156 mutated molecule was apparently functional and able to bind IRBC and oxidized LDL.