This family encodes a 25 kDa protein that is phosphorylated by a Ser/Thr-Pro kinase [1]. It has been described as a brain specific protein, but it is found in Tetrahymena thermophila.

1: A novel brain-specific 25 kDa protein (p25) is phosphorylated by a Ser/Thr-Pro kinase (TPK II) from tau protein kinase fractions. Takahashi M, Tomizawa K, Ishiguro K, Sato K, Omori A, Sato S, Shiratsuchi A, Uchida T, Imahori K; FEBS Lett 1991;289:37-43. PMID:1909972