The best candidate is the merozoite surface protein (MSP) 1complex, comprising the most abundant proteins of the merozoite exterior, and known to be cleaved and, in most part, shed during invasion17. Beneath the mero-zoite PM, attached to it by filamentous cross-bridges12,lie two more membranes, the three together forming the pellicle. The deeper two membranes are the outer and inner leaves of a flattened membranous sac