Microtubule-associated protein (MAP) that regulates the orientation of interphase cortical microtubules. Able to bundle microtubules in vitro. Modulates both rotational polarity and anisotropic cell expansion during organ growth. Promotes clockwise root and etiolated hypocotyls coiling, clockwise leaf curling, but left-handed petiole twisting. Expressed in seedlings, cotyledons, hypocotyls, roots, leaves, flowers, inflorescence stems and siliques. Belongs to the TPX2 family.