A large family of signal-transducing adaptor proteins present in wide variety of eukaryotes. They are phosphoserine and phosphothreonine binding proteins involved in important cellular processes including signal transduction; cell cycle control; apoptosis; and cellular stress responses. 14-3-3 proteins function by interacting with other signal-transducing proteins and effecting changes in their enzymatic activity and subcellular localization. The name 14-3-3 derives from numerical designations used in the original fractionation patterns of the proteins.