A cDNA clone (AtPUMP) encoding a plant uncoupling mitochondrial protein was isolated from Arabidopsis thaliana. The cDNA contains an open reading frame of 921 nucleotides encoding 306 amino acids (predicted molecular weight 32708), The predicted polypeptide is 81% identical and 89% similar to the potato UCP-like protein, and includes an energy transfer protein motif common to mitochondrial transporters. The AtPUMP gene exists as a single cop! in the Arabidopsis genome, The corresponding transcript was expressed in all tissues and was strongly induced by cold treatment. We suggest that the putative AtPUMP protein may play a role in heat-requiring physiological events in Arabidopsis. (C) 1998 Federation of European Biochemical Societies.4293403406