title: The Cytoplasmic Region of Plasmodium falciparum SURFIN4.2 Is Required for Transport from Maurer's Clefts to the Red Blood Cell Surface.
abstract: BACKGROUND
  Plasmodium, the causative agent of malaria, exports many proteins to the surface of the infected red blood cell (iRBC) in order to modify it toward a structure more suitable for parasite development and survival. One such exported protein, SURFIN4.2, from the parasite of human malignant malaria, P. falciparum, was identified in the trypsin-cleaved protein fraction from the iRBC surface, and is thereby inferred to be exposed on the iRBC surface. SURFIN4.2 also localize to Maurer's clefts-parasite-derived membranous structures established in the RBC cytoplasm and tethered to the RBC membrane-and their role in trafficking suggests that they are a pathway for SURFIN4.2 transport to the iRBC surface. It has not been determined the participation of protein domains and motifs within SURFIN4.2 in transport from Maurer's clefts to the iRBC surface; and herein we examined if the SURFIN4.2 intracellular region containing tryptophan-rich (WR) domain is required for its exposure on the iRBC surface.
  
  
  RESULTS
  We generated two transgenic parasite lines which express modified SURFIN4.2, with or without a part of the intracellular region. Both recombinant SURFIN4.2 proteins were exported to Maurer's clefts. However, only SURFIN4.2 possessing the intracellular region was efficiently cleaved by surface treatment of iRBC with proteinase K.
  
  
  CONCLUSIONS
  These results indicate that SURFIN4.2 is exposed on the iRBC surface and that the intracellular region containing WR domain plays a role on the transport from Maurer's clefts to the iRBC membrane.
authors: Section of Environmental Parasitology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo, Tokyo 113-0034, Japan; Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
authors: Wataru
authors: W
authors: Kagaya
authors: Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University , Nagasaki, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
authors: Shinya
authors: S
authors: Miyazaki
authors: Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University , Nagasaki, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
authors: Kazuhide
authors: K
authors: Yahata
authors: Section of Environmental Parasitology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University , 1-5-45 Yushima, Bunkyo, Tokyo 113-0034, Japan.
authors: Nobuo
authors: N
authors: Ohta
authors: Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University , Nagasaki, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
authors: Osamu
authors: O
authors: Kaneko
keywords: Maurer’s clefts; Plasmodium falciparum; SURFIN; malaria; protein transport