Preparation and properties of the brain specific protein 14-3-2

A brain specific protein, 14-3-2, has been isolated from bovine brain by the use of ammonium sulfate precipitation, gel filtration on Sephadex G-150, and ion exchange chromatography on DEAE-cellulose and DEAE-Sephadex. It is an acidic protein, in agreement with the high content of glutamic and aspartic acid, that is composed of a single polypeptide chain of mol. wt. 50,000. Immunochemical tests using antiserum to purified 14-3-2 showed that the protein is present in at least 100-fold greater amounts in brain than in any other rat tissue. Furthermore, 14-3-2 was found in brains of a number of vertebrate species, although the antigen is apparently not entirely identical in all species tested. The protein 14-3-2 can be considered to be a species non-specific protein which is neuronal in origin.