Seyfert H M, Tuckoricz A, Interthal H, Koczan D, Hobom G
Forschungsinstitut für die Biologie landwirtschaftlicher Nutztiere, Dummerstorf, Germany.
Gene. 1994 Jun 10;143(2):265-9. doi: 10.1016/0378-1119(94)90108-2.
Lactoferrin (Lf), a ferric ion (Fe3+)-binding glycoprotein, is found most notably in milk, probably to mediate protection against microbial infection of the mammary gland. Based on an initial isolation and sequencing of a complete cDNA of the bovine Lf gene (bLf), the complete gene was obtained from genomic libraries on five overlapping phage lambda EMBL3 clones. A detailed restriction map and the complete exon/intron structure of the gene are presented, together with 1 kb of sequence data of the promoter upstream from the proximal exon. The coding sequence is dispersed over 17 exons spanning 34.5 kb of genomic DNA. While the exons are of similar size, as in other members of the transferrin gene family (Tf), some of the intron sizes are very different. Evolutionary conservation of both exon sizes and their contribution to the various domains of the protein molecule add to the evidence that Lf originated via an internal sequence duplication. The promoter sequence lacks some of the sequence motifs for transcriptional enhancers found in the promoters of human and mouse Lf, suggesting a potential reason for the relatively weak expression of bLf.
乳铁蛋白（Lf）是一种结合铁离子（Fe3+）的糖蛋白，最显著地存在于牛奶中，可能是为了介导对乳腺微生物感染的保护作用。基于牛Lf基因（bLf）完整cDNA的初步分离和测序，从五个重叠的λEMBL3噬菌体基因组文库中获得了完整基因。本文展示了该基因详细的限制性图谱和完整的外显子/内含子结构，以及近端外显子上游启动子的1 kb序列数据。编码序列分布在跨越34.5 kb基因组DNA的17个外显子上。虽然外显子大小与转铁蛋白基因家族（Tf）的其他成员相似，但一些内含子大小差异很大。外显子大小及其对蛋白质分子各个结构域的贡献的进化保守性进一步证明了Lf是通过内部序列重复起源的。启动子序列缺乏在人和小鼠Lf启动子中发现的一些转录增强子序列基序，这表明bLf表达相对较弱的一个潜在原因。
