Molenaar A J, Davis S R, Jack L J, Wilkins R J
Ruakura Research Centre, AgResearch, Hamilton, New Zealand.
Histochem J. 1995 May;27(5):388-94.
Previous in situ hybridization studies from our laboratory have shown that expression of certain milk protein genes, e.g. alpha-lactalbumin, is very high in most parts of the mammary glands of sheep and cattle, while in other areas containing an abundance of fat globules it is virtually zero (Molenaar et al., 1992). One possible explanation is that some areas of the mammary gland are dedicated to protein synthesis and some to fat synthesis. To check this possibility, the cRNA for butyrophilin, a milk-fat globule membrane protein, and hence a putative marker of milk fat synthesis, was used as a probe in in situ hybridization studies. The results show quite clearly that the patterns of expression for this gene are similar, cell type for cell type, as those for milk protein genes such as alpha-lactalbumin and alpha S1casein. In addition, we found that butyrophilin gene expression more closely matches that of alpha S1casein than that of alpha-lactalbumin. If it is shown in the future that butyrophilin is indeed a marker for milk fat synthesis, then these results support the current assumption that fat and protein synthesis do occur in the same cell.
我们实验室之前的原位杂交研究表明，某些乳蛋白基因，如α-乳白蛋白，在绵羊和牛乳腺的大部分区域表达非常高，而在其他含有大量脂肪球的区域其表达几乎为零（莫伦纳尔等人，1992年）。一种可能的解释是，乳腺的一些区域专门用于蛋白质合成，而一些区域专门用于脂肪合成。为了验证这种可能性，将嗜乳脂蛋白（一种乳脂肪球膜蛋白，因此被认为是乳脂肪合成的标志物）的cRNA用作原位杂交研究的探针。结果非常清楚地表明，该基因的表达模式在细胞类型上与α-乳白蛋白和αS1酪蛋白等乳蛋白基因的表达模式相似。此外，我们发现嗜乳脂蛋白基因的表达与αS1酪蛋白的表达比与α-乳白蛋白的表达更匹配。如果未来证明嗜乳脂蛋白确实是乳脂肪合成的标志物，那么这些结果支持了目前脂肪和蛋白质合成确实发生在同一细胞中的假设。
