Johnson G V, Jope R S, Binder L I
Department of Neurology, University of Alabama, Birmingham 35294.
Biochem Biophys Res Commun. 1989 Sep 29;163(3):1505-11. doi: 10.1016/0006-291x(89)91150-9.
The calpain-induced proteolysis of tau associated with twice-cycled microtubules or from a total brain heat-stable fraction was studied. Twice-cycled microtubule tau was rapidly hydrolyzed by calpain. In contrast, tau purified from the total brain heat-stable fraction was very resistant to degradation by calpain. These results clearly demonstrate that there are at least 2 populations of tau in the brain based on calpain-sensitivity, a calpain-sensitive form that is associated with microtubules and a calpain-resistant form that may represent another population of tau in the brain.
