Fig. 3.
Protozoans contain atypical RCC1 proteins. Shown are domain profiles (www.expasy.org/prosite) illustrating the RCC1 repeats present in RCC1 orthologs from various organisms. Later branching eukaryotes (shown are Homo sapiens, Saccharomyces cerevisiae, and Arabidopsis thaliana) contain the typical RCC1 structure with seven tandem repeats of 50–60 aa (shown as ovals). Apicomplexan parasites display a dispersed arrangement of the RCC1 domains within the protein. In Plasmodium falciparum, there are six repeats within the 1,327-aa protein. The Cryptosporidium hominus ortholog contains four RCC1 repeats. The T. annulata and T. gondii ortholog contain a zinc finger motif (boxed). The human RCC1 protein was used to BLASTp search the National Center for Biotechnology Information database of sequenced protozoa. The proteins with the highest similarity and predicted to be localized to the nucleus are shown.