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Figure 1 | Malaria Journal

Figure 1

From: Antibodies against multiple merozoite surface antigens of the human malaria parasite Plasmodium falciparum inhibit parasite maturation and red blood cell invasion

Figure 1

Primary structure and processing of P. falciparum 3D7 MSP-1, MSP-6, MSP-7 and AMA-1. SS, signal sequence; GA, GPI anchor; PS, pro-sequence; TM, transmembrane domain. (A) Outline of the MSP-1 precursor. The grey arrows indicate the sites of primary processing of the precursor protein into its major subunits MSP-183, MSP-130, MSP-138, and MSP-142 as defined by Stafford et al., 1994 [42] and Koussis et al., 2009 [6]. A secondary proteolytic cleavage mediated by PfSUB2 (black arrow) occurs during invasion, cleaving MSP-142 into MSP-133 and MSP-119. (B) AMA-1 is synthesized as an 83 kDa precursor protein containing a C-terminal transmembrane domain (TM). After targeting to the micronemes the N-terminal pro-sequence (PS) is removed, resulting in AMA-166, which appears at the merozoite surface at the time of schizont rupture. During invasion AMA-166 is proteolytically cleaved by PfSUB2 (black arrow) resulting in release of AMA-148/44 [14, 15]. MSP-6 (C) and MSP-7 (D) are peripheral merozoite surface proteins, membrane-bound through non-covalent associations with MSP-1. MSP-6 is processed into MSP-636. MSP-7 is initially cleaved into MSP-733 [9]. Around the time of merozoite release from the newly ruptured schizont, MSP-733 is further cleaved into MSP-722 and MSP-719 [9, 10].

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