Characterization of TgICMAP1 Figure 7. The first 474 amino acids of TgICMAP1 are important for intra-conoid MT association in T. gondii. Interphase parasites expressing eGFP fusions (green) of full-length TgICMAP1 (A), TgICMAP11–474 (B), and TgICMAP1455–1231 (C) were labeled with anti-IMC1 antibody (red). EGFP-TgICMAP11–474 is localized to the intra-conoid MTs (green arrows). However, it displays stronger localization to the basal complex (inset) in comparison to eGFP-TgICMAP1. Its cytoplasmic pool is also more prominent than that of eGFP-TgICMAP1. eGFP -TgICMAP1455–1231 is localized predominantly to the nucleus and cytosol. The insets are at 2.56 magnification. Scale bars = 2 mm. doi:10.1371/journal.pone.0007406.g007 membrane pellicle [31–33]. In addition to the mother intra-conoid MTs, eGFP-TgICMAP1 was localized to the daughter intra-conoid MTs and the duplicated centriole/spindle pole assembly. There- fore, the daughter intra-conoid MTs are present in the daughter parasites as they are formed within the mother. Discussion Unlike mammalian cells in culture where the majority of the MTs in the cell are highly dynamic, the tubulin containing structures in T. gondii are extraordinarily stable in interphase parasites. The apical complex and the cortical MTs, for example, remain intact after harsh detergent extractions (c.f. Figure 6D–F) [1,3,7] and are highly resistant to MT depolymerization drugs such as oryzalin and nocodazole [5]. The stability of these tubulin containing structures provides stiffness to the parasite cortex, thus they are important in maintaining the parasite shape and are likely to be important for basic parasite functions such as directional movement and invasion. MT binding proteins are central players in regulating MT stability and function. In this work, we report the PLoS ONE | www.plosone.org 7 October 2009 | Volume 4 | Issue 10 | e7406