Associations between lipoxygenases (Lox) and 14-3-3 proteins were demonstrated by two different methods. First, immunoprecipitation experiments, using isoenzyme-specific monoclonal Lox antibodies, showed that 14-3-3 proteins co-precipitate with 13-Lox, but not with the 9-Lox from barley. Second, interactions between 13-Lox and 14-3-3 were established by surface plasmon resonance studies, showing that 13-Lox binds with 14-3-3 proteins in a concentration-dependent manner. The interactions between 14-3-3 proteins and 13-Lox may reveal their role during plant development. Copyright (C) 2000 Federation of European Biochemical Societies. Molecular Sequence Numbers: GENBANK: L35931, L37358, X62388, X93170, Y14200; Chemicals/CAS: 13-lipoxygenase, EC 1.13.11.-; 14-3-3 Proteins; Antibodies, Monoclonal; Isoenzymes; Lipoxygenase, EC 1.13.11.12; Proteins; Recombinant Proteins; Tyrosine 3-Monooxygenase, EC 1.14.16.2