Peptide derived from microtubule binding repeat of Tau protein. Self-assembles into 30-55 nm paired helical filaments (PHFs) even in the absense of inducers. Cytotoxic in multiple cell lines including cortical neurons, cerebellar granular neurons, neuroblastoma cells, kidney fibroblasts and HEK293 cells. Co-localizes with pathological hyperphosphorylated forms of tau in vitro. Cell permeable. MW (observed): 2195.66.