De Leo A A, Lefevre C, Topcic D, Pharo E, Cheng J F, Frappell P, Westerman M, Graves J A M, Nicholas K R
CRC for Innovative Dairy Products, Department of Zoology, The University of Melbourne, Melbourne Australia.
Cytogenet Genome Res. 2006;115(1):62-9. doi: 10.1159/000094802.
We report the first isolation and sequencing of genomic BAC clones containing the marsupial milk protein genes Whey Acidic Protein (WAP) and Early Lactation Protein (ELP). The stripe-faced dunnart WAPgene sequence contained five exons, the middle three of which code for the WAPmotifs and four disulphide core domains which characterize WAP. The dunnart ELPgene sequence contained three exons encoding a protein with a Kunitz motif common to serine protease inhibitors. Fluorescence in situ hybridization located the WAPgene to chromosome 1p in the stripe-faced dunnart, and the ELPgene to 2q. Northern blot analysis of lactating mammary tissue of the closely related fat-tailed dunnart has shown asynchronous expression of these milk protein genes. ELPwas expressed at only the earlier phase of lactation and WAPonly at the later phase of lactation, in contrast to beta-lactoglobulin (BLG) and alpha-lactalbumin (ALA) genes, which were expressed in both phases of lactation. This asynchronous expression during the lactation cycle in the fat-tailed dunnart is similar to other marsupials and it probably represents a pattern that is ancestral to Australian marsupials.
我们报告了首次分离和测序包含有袋类动物乳蛋白基因乳清酸性蛋白（WAP）和早期泌乳蛋白（ELP）的基因组BAC克隆。条纹脸袋鼬的WAP基因序列包含五个外显子，其中中间三个编码WAP基序以及四个表征WAP的二硫键核心结构域。袋鼬的ELP基因序列包含三个外显子，编码一种含有丝氨酸蛋白酶抑制剂共有的Kunitz基序的蛋白质。荧光原位杂交将WAP基因定位到条纹脸袋鼬的1号染色体短臂，将ELP基因定位到2号染色体长臂。对亲缘关系密切的肥尾袋鼬泌乳乳腺组织的Northern印迹分析表明，这些乳蛋白基因存在异步表达。与在泌乳两个阶段均表达的β-乳球蛋白（BLG）和α-乳白蛋白（ALA）基因相反，ELP仅在泌乳早期表达，WAP仅在泌乳后期表达。肥尾袋鼬泌乳周期中的这种异步表达与其他有袋类动物相似，它可能代表了澳大利亚有袋类动物的一种祖先模式。
