The Nature of the Two Proteins of Brain Specific Antigen 14‐3‐2

The three isoenzymes of rat brain enolase (2‐phospho d ‐glycerate hydrolase EC 4.2.1.11.) χχ, χγ and γγ were separated by ion‐exchange chromatography and were tested for reaction with an antiserum against brain specific antigen 14‐3‐2. This monospecific antiserum affects the enolase activity of only the χγ and γγ isoenzymes. Immunoelectrophoretic experiments show that the two proteins which react as 14‐3‐2 both contain γ enolase subunits, and one of these also contains χ enolase subunits. It is concluded that the 14‐3‐2 antigen and the γ enolase subunit are identical, and that the two proteins which react immunologically as 14‐3‐2 are the χγ and γγ enolase isoenzymes.