(A) TSR-containing proteins in Plasmodium. TRAP-family proteins are marked with a red bar, whereas TRAP-related proteins are indicated by a green bar and other TSR-containing proteins by a blue bar. TRP1 is encircled by a dashed line (top right). Thrombospondin repeats are shown as blue boxes (labeled with T) and Von Willebrandt factor like A-domains are depicted as red hexagons (labeled with A). Signal peptides are shown as black boxes and transmembrane domains as light green ovals. CSP possesses a GPI-anchor (grey triangle), whereas SPATR harbors an EGF-domain (white box). Conserved tryptophans are indicated with a W. Protein schemes are not drawn to scale and amino acid numbers refer to P. berghei proteins. (B) Protein model of PbTRP1 (PBANKA_0707900; 896 amino acids) in comparison to PbTRAP (PBANKA_1349800, 606 amino acids, not to scale). Both proteins contain a signal peptide (SP), a thrombospondin type-I repeat (TSR), a transmembrane domain (TMD) and a cytoplasmic tail domain (CTD), but TRP1 lacks the conserved tryptophan (W) that is typically found at the C-terminus of TRAP-family proteins. Instead of the Von Willebrandt factor-like A-domain in TRAP, TRP1 contains a long N-terminal extension. (C) Multiple sequence alignment of the PbTRP1 TSR with TSRs from the TRAP-family (PbTRAP, TgMIC2, PbCTRP, PbS6 and PbTLP) and other TSR-containing proteins (PbTRAMP and PbCSP). (D) Length (in amino acids) and isoelectric point (pI) of the CTDs of TRP1 and TRAP from different Plasmodium species.