Wu L S, Wang L D, Chen P W, Chen L J, Tzen J T
Graduate Institute of Agricultural Biotechnology National Chung-Hsing University, Taichung, Taiwan 40227.
J Biochem. 1998 Mar;123(3):386-91. doi: 10.1093/oxfordjournals.jbchem.a021949.
Oleosins are hydrophobic proteins localized abundantly in the oil bodies of plant seeds. Two distinct oleosin isoforms of molecular masses 18 and 16 kDa are present in rice oil bodies. These isoforms were found in similar ratio in rice embryos and aleurone layers. To survey potential DNA sequences involved in the activation of oleosin genes, a genomic clone of rice 18 kDa oleosin was sequenced, and its 5'-flanking region was compared with that of the known rice 16 kDa oleosin gene. Corresponding mRNAs of the two rice oleosin isoforms appeared seven days after pollination and vanished in mature seeds. Triacylglycerols and oleosins were accumulated concomitantly in maturing rice reeds in accord with the active assembly of oil bodies, and partly mobilized in postgerminative seedlings. Approximately 60% of the stored triacylglycerols in rice were not utilized: while the majority of oil bodies in embryos were mobilized in five days after imbibition, those in aleurone layers remained intact in postgerminative seedlings.
油质蛋白是一类疏水性蛋白质，大量存在于植物种子的油体中。在水稻油体中存在两种不同的分子量分别为18 kDa和16 kDa的油质蛋白异构体。这些异构体在水稻胚和糊粉层中的比例相似。为了探究参与油质蛋白基因激活的潜在DNA序列，对水稻18 kDa油质蛋白的基因组克隆进行了测序，并将其5'侧翼区与已知的水稻16 kDa油质蛋白基因的5'侧翼区进行了比较。两种水稻油质蛋白异构体的相应mRNA在授粉后7天出现，并在成熟种子中消失。三酰甘油和油质蛋白在成熟水稻颖果中随着油体的活跃组装而同时积累，并在种子萌发后的幼苗中部分被动员。水稻中约60%储存的三酰甘油未被利用：虽然胚中的大多数油体在吸胀后5天内被动员，但糊粉层中的油体在种子萌发后的幼苗中保持完整。
