Serine/threonine kinase which is able to phosphorylate TAU on serine, threonine and tyrosine residues. Induces aggregation of TAU. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Divalent metal cations. Mg(2+) or, to a lesser extent, Mn(2+), but not Ca(2+) or Zn(2+). Expressed in the brain, particularly in cortical and hippocampal neurons. Weakly expressed in spinal cord and testis. No expression in adipose tissue, bladder, cervix, colon, esophagus, heart, kidney, liver, lung, ovary, placenta, prostate, skeletal muscle, small intestine, spleen, testis, thymus, thyroid or trachea. Belongs to the protein kinase superfamily. CK1 Ser/Thr protein kinase family. It is uncertain whether Met-1 or Met-14 is the initiator.