We previously cloned a cDNA for pig lung tetrameric carbonyl reductase which shows significant similarity to a putative 27-kDa protein predicted from the cDNA for murine adipocyte RNA which had been increased in its differentiation [Nakanishi, M., Deyashiki, Y., Nakayama, T., Sato, K. & Hara, A. (1993) Biochem. Biophys. Res. Commun. 194, 1311-1316]. In this investigation, we isolated and sequenced a full-length cDNA for the tetrameric enzyme from a mouse lung cDNA library. It consisted of 984 bp and coded for a protein of 244 amino acid residues, of which 202 residues were identified by protein sequencing. The expression of the cDNA in Escherichia coli resulted in synthesis of a protein structurally and functionally similar to the enzyme purified from mouse lung. The nucleotide sequence of the cDNA was virtually identical to that of the cDNA for the adipocyte 27-kDa protein. Although Northern-blot analysis of mouse tissues showed that enzyme mRNA to be 1.1 kb only in lung, low expression of the mRNA in all the extrapulmonary tissues, including adipose tissue, was demonstrated by a reverse-transcription PCR method. Western-blot analysis also indicated the presence of the enzyme in the adipose tissue. This is the first report on an identification of the putative gene product of adipocytes as tetrameric carbonyl reductase, the expression of which is tissue-specifically regulated.