THE 14-3-3 FAMILY OF PROTEINS were originally isolated by Moore and Perez in 19671. The name originated from the nomenclature of their systematic analysis of brain proteins, which were identified as a series of acidic proteins that had molecular masses of around 30 000 kDa and an isoelectric point of around 5 in the two-dimensional polyacrylamide gel electrophoresis (PAGE) system. Subsequent studies have indicated that the proteins exist in dimeric form. High levels of the proteins were shown to exist in brain, particularly neuronal tissue, and it was initially thought that they were neuronal tissue specific. They have now been shown to be very wMe_ly distributed and low levels are expressed in most mammalian tissues. Proteins that show a high degree of similarity have been cloned and sequenced from a wide range of other eukaryot: ic organisms including plants, insects, amphibians and yeast.