Fig. 5. TgMIC6 is N-terminally processed in the late Golgi. (A,B,C). Double IFA analyzed by confocal microscopy on intracellular parasites expressing mycMIC6. (A) The precursor of mycMIC6 (in red) is detectable only in less than 30% of the vacuoles, whereas all parasites are positive for MIC6 (green). (B) Overlays using -MIC6 (green) and -MIC2 (red). (C) Overlays using -myc (red) and -MIC4 (green). The compartments of the secretory pathway are indicated with arrows. (D) Western blot analysis of lysates from stable transgenic mic6ko parasites transformed with pTMIC6GPI or pTMIC6EGF1-2GPI (MIC6 lacking the first two EGF-like domains and the TMCD domains replaced by a GPI anchoring signal from SAG1). MIC6GPI was targeted to the plasma membrane but nevertheless underwent N-terminal processing. By contrast, the deletion of EGF-1-2 removes the processing site, and no processed form was detectable. (E) Mass spectrometry fragmentation peaks of the MIC6 specific peptide corresponding to the N-terminal cleavage site of the protein.

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