Fig. 5. BCC4 only localizes to the BC during division.

a Schematic representation of BCC4, which only harbors a single coiled-coil region as recognizable domains. b Parasites expressing endogenously C-terminally Myc3-tagged BCC4 were co-stained with β-tubulin antiserum, which shows that BCC4 localizes to the BC right at its formation but is absent from the mature BC. Arrowheads mark the early- and mid-development daughter BCs; asterisk marks the retracting and disassembling mother’s cytoskeleton. DNA is stained with DAPI (blue) and applies to all panels with blue stain. c Co-staining of BCC4-Myc parasites and the T. gondii centrosome (HsCentrin2 antiserum) shows that BCC4 assembles as a ring-like structure at the point of centrosome duplication. The boxed and numbered panels are magnified as indicated and show BCC4 transitioning from an undefined bleb around the centrosome in panels 1 and 2 into a ring as visible in panel 3. d Four color imaging displays the interplay of YFP-MORN1 and BCC4-Myc3 and the centrosomes in early BC formation. At this very early stage of daughter development before completion of spindle pole separation, BCC4 and MORN1 co-localize in an amorphous mass in close apposition to the outer centrosome. Blue dotted line outlines the parasite. e YFP-BCC4 co-localizes with 5xV5-MORN1 in the BC around the midpoint of daughter cell budding, but in contrast to MORN1, BCC4 is absent from the mature BC in the mother parasite (arrowhead). Dark blue dotted lines outline the mothers; light blue dotted lines outline the budding daughters.