遗传
遺傳
유전
HEREDITAS(BEIJING)
2009年
11期
1113-1120
,共8页
猪獾%苦味受体%T2R2基因%克隆%分子进化分析
豬獾%苦味受體%T2R2基因%剋隆%分子進化分析
저환%고미수체%T2R2기인%극륭%분자진화분석
hog badger%bitter taste receptor%T2R2 gene%cloning%molecular phylogenetic analysis
苦味的感知是机体有效的自我保护机制之一,文章采用PCR和克隆测序方法首次从猪獾基因组中获得一全长为1 169 bp的苦味受体T2R2基因DNA序列(GenBank登录号:FJ812727).该序列含有完整的1个外显子(无内含子),大小为915 bp,编码304个氨基酸残基.其蛋白质等电点为9.76,分子量为34.74 kDa.拓扑结构预测显示猪獾T2R2蛋白上含有N-糖基化位点、N-肉豆蔻酰化位点各1个,蛋白激酶C磷酸化位点2个.整个蛋白质多肽链含有7个跨膜螺旋区,4个细胞外区和4个细胞内区.亲水性/疏水性分析表明,猪獾T2R2蛋白质为一疏水性蛋白,其亲水性区段所占比例较小.种间相似性比较显示,猪獾T2R2基因与犬、猫、牛、马、黑猩猩和小鼠的T2R2基因cDNA序列相似性分别为91.4%、90.6%、84.4%、85.4%、83.8%、72.1%, 氨基酸序列相似性分别为85.5%、85.8%、74.0%、77.6%,75.3%、61.5%.核苷酸替换计算和选择性检验结果表明,猪獾T2R2基因与犬、猫、牛、马、黑猩猩和小鼠间存在着强烈的纯净化选择(Purifying selection),即强烈的功能束缚(Functional constraint),进一步分析发现该选择作用实际上主要存在于跨膜区.猪獾、犬、猫、牛、马、黑猩猩和小鼠的T2R2基因外显子核苷酸序列构建的基因树与其物种树的拓扑结构是相一致的,表明T2R2基因适合于构建不同物种间的系统进化树.
苦味的感知是機體有效的自我保護機製之一,文章採用PCR和剋隆測序方法首次從豬獾基因組中穫得一全長為1 169 bp的苦味受體T2R2基因DNA序列(GenBank登錄號:FJ812727).該序列含有完整的1箇外顯子(無內含子),大小為915 bp,編碼304箇氨基痠殘基.其蛋白質等電點為9.76,分子量為34.74 kDa.拓撲結構預測顯示豬獾T2R2蛋白上含有N-糖基化位點、N-肉豆蔻酰化位點各1箇,蛋白激酶C燐痠化位點2箇.整箇蛋白質多肽鏈含有7箇跨膜螺鏇區,4箇細胞外區和4箇細胞內區.親水性/疏水性分析錶明,豬獾T2R2蛋白質為一疏水性蛋白,其親水性區段所佔比例較小.種間相似性比較顯示,豬獾T2R2基因與犬、貓、牛、馬、黑猩猩和小鼠的T2R2基因cDNA序列相似性分彆為91.4%、90.6%、84.4%、85.4%、83.8%、72.1%, 氨基痠序列相似性分彆為85.5%、85.8%、74.0%、77.6%,75.3%、61.5%.覈苷痠替換計算和選擇性檢驗結果錶明,豬獾T2R2基因與犬、貓、牛、馬、黑猩猩和小鼠間存在著彊烈的純淨化選擇(Purifying selection),即彊烈的功能束縳(Functional constraint),進一步分析髮現該選擇作用實際上主要存在于跨膜區.豬獾、犬、貓、牛、馬、黑猩猩和小鼠的T2R2基因外顯子覈苷痠序列構建的基因樹與其物種樹的拓撲結構是相一緻的,錶明T2R2基因適閤于構建不同物種間的繫統進化樹.
고미적감지시궤체유효적자아보호궤제지일,문장채용PCR화극륭측서방법수차종저환기인조중획득일전장위1 169 bp적고미수체T2R2기인DNA서렬(GenBank등록호:FJ812727).해서렬함유완정적1개외현자(무내함자),대소위915 bp,편마304개안기산잔기.기단백질등전점위9.76,분자량위34.74 kDa.탁복결구예측현시저환T2R2단백상함유N-당기화위점、N-육두구선화위점각1개,단백격매C린산화위점2개.정개단백질다태련함유7개과막라선구,4개세포외구화4개세포내구.친수성/소수성분석표명,저환T2R2단백질위일소수성단백,기친수성구단소점비례교소.충간상사성비교현시,저환T2R2기인여견、묘、우、마、흑성성화소서적T2R2기인cDNA서렬상사성분별위91.4%、90.6%、84.4%、85.4%、83.8%、72.1%, 안기산서렬상사성분별위85.5%、85.8%、74.0%、77.6%,75.3%、61.5%.핵감산체환계산화선택성검험결과표명,저환T2R2기인여견、묘、우、마、흑성성화소서간존재착강렬적순정화선택(Purifying selection),즉강렬적공능속박(Functional constraint),진일보분석발현해선택작용실제상주요존재우과막구.저환、견、묘、우、마、흑성성화소서적T2R2기인외현자핵감산서렬구건적기인수여기물충수적탁복결구시상일치적,표명T2R2기인괄합우구건불동물충간적계통진화수.
Recognition of natural bitter toxins through taste is one of the most effective mechanisms of self-safety. An approximate 1 169 bp sequence of the bitter taste receptor T2R2 gene was obtained by PCR and cloning technique from hog badger genomic DNA(GenBank accession number: FJ812727). This sequence contains a complete single exon (without intron) 915 bp in size, which encodes 304 amino acid residues. The isoelectric point (pi) of the protein is 9.76 and its mo-lecular weight is 34.74 kDa. Topology prediction showed that the T2R2 protein contained one N-glycosylation site, one N-myristoylation site, and two potential protein kinase C phosphorylation sites. Additionally, the whole peptide chain was comprised of seven transmembrane helix regions, four extracellular regions, and four intracellular regions. The T2R2 is a hydrophobic protein with a few hydrophilic components. Homology analysis of the T2R2 gene sequences by Clustal Windicated that the cDNA sequence homology of T2R2 gene in hog badger with dog, cat, cattle, horse, chimpanzee, and mouse is 91.4%, 90.6%, 84.4%, 85.4%, 83.8%and 72.1%, respectively, and the homology of amino acid sequence is 85.5%, 85.8%, 74.0%, 77.6%, 75.3% and 61.5%, respectively. The results of nucleotide acid substitution computation and selective test showed that strong purifying selection (functional constraint) occurred between hog badger and the six species, respec-tively, which mainly existed in the transmembrane regions of T2R2. In addition, the Neighbour-Joining tree of T2R2 gene exons from these seven species is consistent with their species tree, indicating that the T2R2 gene is suitable for constructing molecular phylogenetic tree among different species likewise.
