FIGURE 4.

TgCPB does not contribute to TgROP2–4 protein maturation or rhoptry biogenesis. A, RHΔku80, RHΔku80Δcpl, and RHΔku80Δcpb strains were dual-stained with anti-TgROP2–4 and anti-TgCPB catalytic domain antibodies. TgCPB localization is close to but distinct from rhoptries. PVM, parasitophorous vasuole membrane. B, replicating parasites show fragmentation of TgCPB labeled vesicles that are proximal to but usually distinct from apical rhoptries. Panels are in the same order as in A. C and D, electron microscopy of RHΔku80Δcpb parasites revealed normal rhoptry morphology in either newly invaded (C) or replicating T. gondii (D). Bars, 500 nm. DG, dense granules; mi, microneme; PV, parasitophorous vacuole; rh, rhoptry; VAC, vacuolar compartment. E, maturation of TgROP2–4 was compared among RHΔku80, RHΔku80Δcpl, and RHΔku80Δcpb parasites by pulse-chase metabolic labeling and immunoprecipitation. TgROP2–4 maturation showed normal kinetics in TgCPL or TgCPB deletion mutants based on phosphorimage analysis (bars represent S.E. of three independent experiments).