tau protein is a major structural protein of paired helical filaments found in neural lesions associated with Alzheimer's disease.

a protein that helps the functioning of microtubules, which are part of the cell's structural support and help to deliver substances throughout the cell. In Alzheimer's disease, tau is changed in a way that causes it to twist into pairs of helical filaments that collect into tangles.

a special kind of protein that makes the microtubule stable. It is found in an abnormal form as the major component of neurofibrillary tangles. The abnormal form is called phosphorylated tau.