CLONING AND EXPRESSION OF THE PORCINE OBESE GENE

The product of the obese gene, leptin, may be an important regulator o f adiposity via its regulation of feed intake and energy metabolism. P robes were developed using the polymerase chain reaction to analyze ge ne expression and determine the structure of the porcine ob gene. Porc ine ob was expressed in adipose tissue as a 3,100 bp mRNA. Finished pi gs (136 kg) had higher (P < .01) levels of ob mRNA (per unit of beta-a ctin mRNA) in subcutaneous adipose tissue than did growing pigs (60 kg ). Obese gene expression was not detected in tissues other than adipos e depots. A genomic DNA fragment containing the ob gene was isolated f rom a cosmid DNA library. Sequence analysis indicates that the ob gene has three exons. A short untranslated sequence was identified as exon 1 and the amino acid coding sequence was located in the second and th ird exons. The gene structure, intron/exon boundaries, and the amino a cid sequence was highly conserved in mammalian species. The porcine le ptin amino acid sequence was 95%, 92% and 89% similar to cattle, human and mouse leptin sequences, respectively.