Tubulin but not microtubule

The pathogens that cause malaria, cryptosporidiosis, and toxoplasmosis share a baffling common feature: a cone-shaped apical structure called the conoid. Previous research has suggested that the conoid is composed of microtubules and has simultaneously provided evidence that it is not. Now, on page 1039, Hu et al. resolve this longstanding dilemma by demonstrating that the conoid is made of tubulin, but not in the form of classical microtubules. In addition to describing a previously unknown form of cytoskeletal structure, the results could help in the development of new treatments for some of the world's most devastating diseases.

The conoid is part of the apical complex, the defining feature of the phylum Apicomplexa and a structure thought to be involved in host cell invasion by these parasites. Although tubulin was considered the most likely building block of...