Cloning, Expression Of Sheep PRKAG3 Gene And Association Analysis Between Polymorphism And Tan Sheep Meat Quality Traits

The protein kinase adenosine monophosphate-activatedγ3-subunit (PRKAG3) gene encodes a muscle-specic isoform of the regulatory gamma-subunit of adenosine monophosphate-activated protein kinase,which plays a key role in regulating energy homeostasis in eucaryotes.It is well known that mutations in the PRKAG3 gene affect high glycogen content in the porcine skeletal muscle and,consequently,meat quality. The objective of this study was to clone and analyze the sequence of PRKAG3 gene and was to determine expression characteristics of PRKAG3 gene in different tissues of Poll Dorsets sheep with the methods of RT- PCR.,to screen for polymorphisms in the sheep PRKAG3 gene, and explore its possible association with meat traits in seven sheep breeds.The CDS of PRKAG3 gene of sheep were amplified by RT-PCR. The result of homology modeling show that theγ3 protein were consist of four conserved Cystathionineβ-synthase Domain which are allβ-folding and hydrophobic amino acid, plays a key role in regulating AMPK. The homology of sheep PRKAG3 gene with bovine,human, pig and mouse was 96%,84%,82% and 81%respectively. The RT- PCR results showed that the expression level of PRKAG3 gene is highest in muscle, heart, kidney, spleen and liver, from the highest to the lowest.In this study, polymerase chain reaction single-strand composition polymorphism (PCR-SSCP) method was first time used to screene polymorphisms of PRKAG3 gene in seven sheep breeds: Tan,Hu,Hazakh,Hulunbeier, Wuzhumuqin,lanzhoudawei and Poll Dorset. A total of 9 single nucleotide polymorphisms( SNPs) were identified, among which ,3 were in exon 3 and 6 located in introns 6,8,10,11 and.12 three SNPs in the exon 4 were synonymous mutations that only existed in Tan and Hulunbeier show low polymorphisms. The three mutations serperately exist in intron 11 and intron 12, only two alleles were identified in this locus.The polymorphisms information contents were moderate polymorphisms in Tan and Hulunbeier sheeps,and others were in low polymorphisms.The effect of PRKAG3 gene polymorphisms on the sheep meat traits were analyzed by SAS analysis of variance.The result indicated that the primer p3 and p10 loci had a signinficant effect on meat pH and meat clours. Analysisi of variance result show that not only the genotype but also the age factor have influence on the sheep meatclours,pHand IMF.This result may provide a scientific basis for Marker Assisted Selection of sheep meat flavor .