Uncoupling protein (UCP) 2 is a member of the uncouplingprotein family, and it appears to function as an uncoupler of oxidative phosphorylation. To identify cis-acting regulatory elements controlling this gene's expression, we cloned an approx. 6.2-kb region upstream from the translation-initiation site of the mouse UCP2 gene and analysed its transcription activity using chimaeric mouse UCP2 promoter-placental-alkaline-phosphatase (PLAP) reporter-gene constructs. Sequence analysis showed that the 5h-flanking region of the mouse UCP2 gene was not similar to those of mouse UCP1 or UCP3. For the mouse UCP2, the region near the transcription-initiation site lacked the typical TATA box, but was GC-rich, resulting in presence of several potential specificity protein 1 (Sp-1), activator protein (AP)-1 and AP-2 binding sites. The putative regulatory motifs for muscle-regulatory protein (MyoD), brown-fat regulatory element, CCAAT box, cAMP-response element and Y box were also found in the mouse UCP2 promoter region by computerassisted analysis. From the results of Northern-blot analysis and transient expression assay, we found that the mouse UCP2 gene responded to the cAMP-dependent protein kinase α-catalytic