THE 30-KILODALTON PROTEIN PRESENT IN PURIFIED FUSICOCCIN RECEPTOR PREPARATIONS IS A 14-3-3-LIKE PROTEIN

We have recently reported on the purification of the fusicoccin (Pc) r eceptor from corn (Zea mays L.) and ifs identification by photoaffinit y labeling (P. Aducci, A. Ballio, V. Fogliano, M.R. Fullone, M. Marra, N. Proietti [1993] Eur J Biochem 214: 339-345). Pure preparations of FC receptors, obtained under nondenaturing conditions, showed in sodiu m dodecyl sulfate-polyacrylamide gel electrophoresis two doublets of p roteins with apparent molecular masses of 30 and 90 kD. In the present paper we describe the isolation and identification of the primary str ucture of the 30-kD doublet proteins. Sequencing studies of peptides r esulting from the digestion of the 30-kD protein showed a full identit y with a 14-33-like protein from corn, named GF14. The 14-3-3 family i s a class of proteins that is widely distributed in eukaryotes and is known to play various regulatory roles. The 30-kD protein has been imm unologically identified by specific antibodies prepared against a synt hetic peptide based on the determined amino acid sequence. A similar p rotein is recognized in partially purified FC receptor preparations fr om bean and spinach leaves.