An anchor for motoring

Toxoplasma gondii, a parasite that can cause blindness and brain damage in immunocompromised individuals, spreads around the body and penetrates into cells using a bizarre spinning and corkscrewing motility. This motility is not dependent on any easily visible structure, such as a flagellum or lamellipodia, and the cell moves without changing shape. Now, Gaskins et al. (page 383) report the identification of TgGAP45 and TgGAP50, two proteins that may anchor myosin so that the motor can drive this unique form of motility.

The authors began by isolating and raising antibodies to the inner membrane, where the myosin-A (TgMyoA) responsible for motility is thought to hang out. They found TgGAP45, a protein of unknown function. Immunoprecipitation of TgGAP45 yielded TgMyoA, its associated light chain, and TgGAP50, an integral membrane protein. The TgGAP45, TgMyoA, and...