Abstract: 【Objective】The objective of this study is to reveal the biological function of peroxisome proliferator-activated receptor gamma (PPARG) gene in sheep and provide theoretical data for application by cloning PPARG and analyzing its sequence as well as genetic features.【Method】The specific primers on the CDS template of PPARG gene were designed and then the PPARG gene sequence of Lanzhou fat-tail sheep was cloned using RACE and RT-PCR technology. After that, its genetic characteristics were analyzed by bioinformatics methods. 【Results】 The 1 774 bp full-length cDNA of PPARG of Lanzhou fat-tailed sheep (Genbank No.: KF727439) was obtained, in which the length of CDS is 1 428 bp. It encodes 475 amino acids in total. The coding regions on both sides of the wing are respectively provided with 5 '-UTR 131 bp (1-131 nt) and 3' -UTR 214 bp (1560-1774 nt). It was predicted that the molecular weight of PPARG protein of Lanzhou fat-tail sheep is 54.40 kD and its theoretical isoelectric point is 4.94. In addition, its maximum hydrophobic value is 3.600 and minimum hydrophobic value is -2.744. It is a non-transmembrane hydrophobin with no signal peptide, which locates mostly in cytoplasm (65.2%), seldom in nucleus (21.7%), scaffold (4.3%) and peroxisome (4.3%) by the result of subcellular level prediction and does not belong to the secretory protein. Its amino acid sequence contains 26 phosphorylation sites, 0 glycosylation site, 1 ZnF_C4 domain, 1 HOLI domain and 1 LCR domain. Also, its secondary structure is mainly randomly curly. Nucleotide sequence analysis revealed that the gene nucleotide sequence of Lanzhou fat-tail sheep is similar with those of the capra (99%), bos (98%), bubalus (97%), ovis (99%), orcinus (94%), sus (92%) and homo (90%). The similarity of amino acid sequence of PPARG between Lanzhou fat-tailed sheep and capra, bos, bubalus, ovis, orcinus, sus and homo are 100%, 99.8%, 100%, 100%, 98.7%, 98.5% and 97.5%. The phylogenetic tree indicates that Lanzhou fat-tail sheep is close to capra, ovis and bubalus, but far from fish, human and mouse. Base transitions occur in the 486th and 828th sites, which are (C vs. T) and (C vs. A), respectively, but the corresponding amino acids do not change.【Conclusion】The fact that the structure of PPARG of Lanzhou fat-tail sheep highly similar with other species indicates that the gene is highly conservative. It was predicated that most of the PPARG protein synthesises at the ribosome and its function is related to peroxisome. The results are in good agreement with its status of peroxisome proliferator activated receptor. The amino acids sequence of PPARG has 26 protein kinase phosphorylation sites. After phosphorylation some sites will lead to a series of dysfunction and expression of obesity-related genes, such as decreased expression of insulin sensitizing hormone and adiponectin. In PPARG , HOLI (also named LBD ligand) structural domain plays an important role in the process of hormone signal transduction, while ZnF_C4 zinc finger structural domain has the function of combining with lipid, which means that the Ser112 in PPARG zinc finger domain, after phosphorylation by MAPK, can inhibit the PPARG binding with the ligand, thereby reducing the activity of the PPARG protein. Both domains are associated with the differentiation process of lipid. The paper has laid a biological foundation for further study on the function of PPARG in lipid differentiation.

Key words: Lanzhou fat-tailed sheep , PPARG gene , race , bioinformatics analysis