Fig. 2. Antibodies to MORN1 label a structure at the anterior and posterior end of the inner membrane complex (IMC). (A) Anti-MORN1 antiserum reacted specifically with purified HIS-tagged MORN1 (HM1, 42.8 kDa, second band probably represents a dimer) but not MORN2 protein (HM2, 51.5 kDa) in western blot analysis. A band of slightly smaller molecular mass consistent with native MORN1 was detected in parasite lysates (RH, 40.9 kDa); no reactivity was observed with the preimmune serum (PI). (B-D) In immunofluorescence assays this antiserum (green) produces staining at the apical and posterior end of the IMC (red) of the parasite as well as a dot mid-cell (anterior label indicated by arrowheads). (E-G) In dividing cells daughter IMCs are equally labeled. An additional structure in the IMC, most probably the micropore, is also detected (arrow).