FIG. 6.

GRA14 behaves as an integral membrane protein by biochemical fractionation. (A) Triton X-114 phase partitioning showing that GRA14 is found preferentially in the detergent (membrane) fraction with the GPI-anchored SAG1, whereas the soluble marker ROP1 is found in the aqueous (soluble) phase. (B) Cell fractionation and carbonate extraction of 24-h-infected cells revealed that secreted GRA14 is tightly associated with membranes, along with the GPI-anchored SAG1. Sup, supernatant. (C) Carbonate extraction of extracellular parasites revealed that a portion of GRA14 partitions with the soluble fraction, whereas the membrane protein SAG1 is completely membrane associated. The GRA14-HA strain was used for panels A and C, and RH strain parasites were used for panel B.