Structure of a 14-3-3 protein and implications for coordination of multiple signalling pathways

A BROAD range of organisms and tissues contain 14-3-3 proteins, which have been associated with many diverse functions including critical roles in signal transduction pathways, exocytosis and cell cycle regulation 1 . We report here the crystal structure of the human T-cell 14-3-3 isoform (τ) dimer at 2.6 Å resolution. Each monomer ( M r 28K) is composed of an unusual arrangement of nine antiparallel α-helices organized as two structural domains. The dimer creates a large, negatively charged channel approximately 35 Å broad, 35 Å wide and 20 Å deep. Overall, invariant residues line the interior of this channel whereas the more variable residues are distributed on the outer surface. At the base of this channel is a 16-residue segment of 14-3-3 which has been implicated in the binding of 14-3-3 to protein kinase C.