Abstract: To explore the biological function of acetyl-coenzyme A acyltransferase 1 (ACAA1) gene,and determine the expression difference of ACAA1 gene in different tissues of Small-tail Han sheep,in this experiment,the total RNA was extracted from heart,liver,stomach,duodenum,small intestine,longissimus dorsi muscle and subcutaneous fat tissue of Small-tail Han sheep.Primers were designed based on the sequence of ACAA1 gene in sheep published in GenBank (accession No.:XM_004018227.3).The complete CDS of ACAA1 gene in Small-tail Han sheep was obtained by RT-PCR and molecular cloning technology,and bioinformatics analysis was carried out.Real-time PCR was used to detect the expression difference of ACAA1 gene in different tissues of Small-tail Han sheep.The results showed that the length of ACAA1 gene CDS in Small-tail Han sheep was 1 071 bp,encoding 356 amino acids,the amino acid sequence of ACAA1 gene in Small-tail Han sheep had the highest homology with Ovis aries and Capra hircus,which were about 100%,and the homology with Macaca fascicularis,Theropithecus gelada and Sus scrofa were 93.0%.The results of phylogenetic tree showed that Small-tail Han sheep was located in a branch with sheep and goat,the relationship was closer,and the relationship with the Manis javanica and Theropithecus gelada was far away,the homology among the species was higher,and the conservation was stronger.The molecular weight of ACAA1 protein was 36.92 ku,the molecular formula was C₁₆₀₃H₂₆₃₈N₄₅₈O₅₀₁S₁₈,the theoretical isoelectric point was 7.48,the half-life was 30 h,the extinction coefficient was 9 440,the stability coefficient was 40.88,and the fat solubility coefficient was 92.67,the hydrophilic amino acid residue was about 58%,this protein was an unstable alkaline fat-soluble hydrophilic protein.There was no transmembrane structure and signal peptide,not secreted protein.It mainly distributed in peroxisomes,there were 25 phosphorylation sites,3 potential N-glycosylation sites and 4 O-glycosylation sites;The secondary structure of ACAA1 protein contained alpha helix (37.92%),beta fold (12.64%) and random coil (49.44%),which was consistent with the tertiary structural results.Real-time PCR results showed that ACAA1 gene was expressed in different tissues of Small-tail Han sheep,and the expression levels were relatively higher in liver,subcutaneous fat and small intestine.This results provided a basis for further exploration of the biological function of ACAA1 gene in Small-tail Han sheep and screening for candidate genes related to meat quality.

Key words: Small-tail Han sheep; ACAA1 gene; cloning; bioinformatics analysis; tissue expression