The auxin-binding protein Nt-ERabp1 alone activates an auxin-like transduction pathway

Hyperpolarization of tobacco protoplasts is amongst the earliest auxin resp onses described. It has been proposed that the auxin-binding protein, ABP1, or a related protein could be involved in the first step of auxin percepti on at the plasma membrane. Using for the first time homologous conditions f or interaction between the protein Nt-ERabp1 or a synthetic peptide corresp onding to the C-terminus and tobacco protoplasts, se have demonstrated that both can induce the hyperpolarization response. The results show that Nt-E Rabp1 or the C-terminal peptide alone activates the auxin pathway from the outer face of the plasma membrane. (C) 1999 Federation of European Biochemi cal Societies.