Canine mitochondrial uncoupling proteins: structure and mRNA expression of three isoforms in adult beagles

• Published in: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology 2002-03, Vol.131 (3), p.483-489
• Main Authors: Ishioka, Katsumi, Kanehira, Katsushi, Sasaki, Noriyasu, Kitamura, Hiroshi, Kimura, Kazuhiro, Saito, Masayuki
• Format: Article
• Language: English
• Subjects: Adipose tissue; Adipose Tissue - metabolism; Amino Acid Sequence; Animals; Blotting, Northern; Carrier Proteins - genetics; Carrier Proteins - metabolism; cDNA cloning; Cloning, Molecular; Companion animals; Dogs; Dogs - metabolism; Ion Channels; Membrane Proteins - genetics; Membrane Proteins - metabolism; Membrane Transport Proteins; Mitochondria; Mitochondria - metabolism; Mitochondrial Proteins; Molecular Sequence Data; Muscle, Skeletal - metabolism; Obesity; Protein Isoforms - genetics; Protein Isoforms - metabolism; Proteins - genetics; Proteins - metabolism; RNA, Messenger - metabolism; Sequence Homology, Amino Acid; Skeletal muscle; Tissue Distribution; UCP1 protein; UCP2 protein; UCP3 protein; Uncoupling protein; Uncoupling Protein 1; Uncoupling Protein 2; Uncoupling Protein 3; uncoupling proteins
• ISSN: 1096-4959; 1879-1107
• DOI: 10.1016/S1096-4959(02)00004-0

Uncoupling proteins (UCPs) are members of the mitochondrial transporter family that dissipate the proton gradient as heat more than via ATP synthesis. In the present study, nucleotide and amino acid sequences of UCPs 1, 2 and 3 of a dog were determined, and their mRNA expression in various peripheral tissues was examined. The sequences were highly (76–97%) homologous to those of other species. Although lower homologies (60–74%) were found when compared among the three canine UCPs, their deduced amino acid sequences had some common domains, such as three mitochondrial carrier protein motifs, six transmembrane α-helix domains, and putative purine nucleotide binding domains. By Northern blot analyses, UCP1 mRNA was not detected in any tissues examined. UCP2 mRNA was expressed in most tissues, particularly abundantly in adipose tissue, spleen and lung. Two sizes of UCP3 mRNA were found exclusively in heart and skeletal muscle. These results suggest that canine UCPs have uncoupling activity, and are involved in the regulation of metabolic heat production and/or energy expenditure, as do those of other species.