Characterization of Arabidopsis AtAMT2, a novel ammonium transporter in plants

We have cloned and characterized the first member of a novel family of ammo nium transporters in plants: AtAMT2 from Arabidopsis thaliana. AtAMT2 is mo re closely related to bacterial ammonium transporters than to plant transpo rters of the AMT1 family. The protein was expressed and functionally charac terized in yeast. AtAMT2 transported ammonium in an energy-dependent manner . In contrast to transporters of the AMT1 family, however, AtAMT2 did not t ransport the ammonium analogue, methylammonium. AtAMT2 was expressed more h ighly in shoots than roots and was subject to nitrogen regulation. (C) 2000 Federation of European Biochemical Societies.