Demmer J, Stasiuk S J, Adamski F M, Grigor M R
Dairy Science Group, AgResearch, Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand.
Biochim Biophys Acta. 1999 Apr 14;1445(1):65-74. doi: 10.1016/s0167-4781(99)00042-1.
Transferrin and ferritin cDNAs have been isolated and characterised from the common brushtail possum (Trichosurus vulpecula), the first marsupial examples of these genes. The transferrin cDNA encodes a 711 amino acid pre-protein which shows high levels of amino acid identity with eutherian transferrins (58-60%) and lactoferrins (54-56%). Phylogenetic analysis suggests that the possum transferrin has evolved independently along a pathway distinct from that of the eutherian transferrins and lactoferrins. Possum H-ferritin is a 182 residue protein which shares 86-94% amino acid identity with mammalian, avian and amphibian sequences. Ferritin mRNA was detected in all tissues tested, whereas transferrin was highly expressed in possum liver and mammary gland, and at lower levels in heart, testis and lung. In the possum mammary gland, ferritin mRNA was expressed throughout lactation with higher levels during the first 30 days which coincides with the high iron concentration of milk at this time. The transferrin gene was differentially expressed during lactation with peak mRNA levels detected during the first 6 days of lactation and after day 106 throughout late lactation. The pattern of transferrin mRNA expression in the mammary gland was identical to that of another whey protein, the late lactation protein, suggesting that the transcription of these genes may be regulated by a similar mechanism in this tissue.
已从帚尾袋貂（Trichosurus vulpecula）中分离并鉴定出转铁蛋白和铁蛋白的cDNA，这是这些基因在有袋类动物中的首个实例。转铁蛋白cDNA编码一种711个氨基酸的前体蛋白，与真兽类转铁蛋白（58 - 60%）和乳铁蛋白（54 - 56%）具有高度的氨基酸同一性。系统发育分析表明，袋貂转铁蛋白是沿着一条与真兽类转铁蛋白和乳铁蛋白不同的途径独立进化的。袋貂H - 铁蛋白是一种由182个残基组成的蛋白质，与哺乳动物、鸟类和两栖动物的序列具有86 - 94%的氨基酸同一性。在所有测试组织中均检测到铁蛋白mRNA，而转铁蛋白在袋貂肝脏和乳腺中高度表达，在心脏、睾丸和肺中表达水平较低。在袋貂乳腺中，铁蛋白mRNA在整个哺乳期均有表达，在前30天表达水平较高，这与此时乳汁中铁的高浓度相吻合。转铁蛋白基因在哺乳期差异表达，在哺乳期的前6天以及整个后期哺乳期的第106天后检测到mRNA水平峰值。乳腺中转铁蛋白mRNA的表达模式与另一种乳清蛋白——后期泌乳蛋白相同，这表明这些基因在该组织中的转录可能受相似机制调控。
