SIMILARITY OF THE NUCLEOTIDE-SEQUENCES OF RAT ALPHA-LACTALBUMIN AND CHICKEN LYSOZYME GENES
SIMILARITY OF THE NUCLEOTIDE-SEQUENCES OF RAT ALPHA-LACTALBUMIN AND CHICKEN LYSOZYME GENES
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DOI：
10.1038/308377a0
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发表时间：
1984-01-01
期刊：
影响因子：
64.8
通讯作者：
SAFAYA, SK
中科院分区：
文献类型：
--
作者：
QASBA, PK;SAFAYA, SK
α-乳清蛋白（α-LA）是一种与半乳糖基转移酶相互作用的乳蛋白，以促进半乳糖转移至葡萄糖的方式改变其底物特异性，从而产生β-1 β 4糖苷键和乳糖合成1，2。溶菌酶是一种催化多糖中β-1 β 4糖苷键水解的酶，已显示与α-LA在结构上相关，并提出它们来自共同的祖先基因3。为了比较它们的进化关系，我们在此报道了大鼠α-LA基因的全核苷酸序列，包括其5′-侧翼序列，并将其基因结构与鸡卵清溶菌酶基因进行了比较4。这两个基因在相似的位置都含有三个内含子。这两个基因的前三个外显子具有相似的核苷酸序列。α-LA的第四外显子部分编码蛋白质的C-末端残基，是其与半乳糖基转移酶5，6相互作用所必需的，它与溶菌酶基因的相应外显子明显不同，并且前面有两个（TG）n重复序列。
α-Lactalbumin (α-LA) is a milk protein that interacts with the enzyme galactosyltransferase, modifying its substrate specificity in a way which promotes the transfer of galactose to glucose, resulting in aβ–1→4 glycosidic linkage and the synthesis of lactose1,2. Lysozyme, an enzyme which catalyses the hydrolysis of aβ–1→4 glycosidic linkage in polysaccharides, has been shown to be structurally related toα-LA and it has been proposed that they have arisen from a common ancestral gene3. To compare their evolutionary relationships, we report here the complete nucleotide sequence of the ratα-LA gene, including its 5′-flanking sequences, and compare its gene structure with the chicken egg-white lysozyme gene4. Both genes contain three introns at similar positions. The first three exons of the two genes have similar nucleotide sequences. The fourth exon ofα-LA, which partly codes for the C-terminal residues of the protein, essential for its interaction with galactosyltransferase5,6, is markedly different from the corresponding exon of the lysozyme gene and is preceded by two (TG)nrepeats.