水稻胚乳甲壳素结合蛋白(ES-CBP)在发育种子中的组织专一性累积及其在萌发时的降解(英文)

Tissue-Specific Accumulation of Rice Endosperm Chitin-Binding Protein (ES-CBP) in Developing Seeds and Its Degradation in Germinating Seeds

免设印迹表明,水稻 ES—CBP(en—dosperm chitin—binding Protein)是胚乳专一性蛋白。蛋白休用NaCl提取后再用TritonX—100提取,所得的两个组份在作免疫印迹时,均能与抗ES—CBP的抗血清起反应,表明这种细胞器的衬质(matrix)和膜部分部有ES—CBP存在。免疫印迹还表明,在开花后7d(7DPA)的水稻种于胚乳中已经累积了相当多的 ES—CBP。在7～30 DPA之问.ES—CBP在胚乳总蛋白中的相对水平随着种子发育而下降。这些结果表明,ES—CBP在7DPA以前的胚乳中的累积是相对活跃的。水稻种子贮藏蛋白在7DPA以后累积最快,这时胚乳中已经累积了相当多的ES—CBP。种子萌发后2d(2DPG)时,ES—CBP已有明显的降解。到7DPG,胚乳中只剩下少量的甲壳素结合蛋白。ES—CBP这样的累积和降解模式支持了该甲壳素结合蛋白是水稻胚乳中蛋白体组织者的假说。

Rice ES-CBP appeared to be specif-ic for the endosperm. as demonstrated by im-munoblotting. Both the NaC1-extracted frac-tion of protein bodies. and the fraction ex-tracted with Triton X-- 100 from the residueafter extraction with NaC1. reacted with anti-serum against ES-CBP on immunoblots. sug-gesting that both the matrix and the mem-brane of these storage organelles contain ES-CBP. By 7 DPA (days post anthesis) a sig-nificant amount of ES-CBP in rice endospermhad already accumulated, as demonstrtated byimmunoblotting. From then on the relativelevel of ES-CBP in total endosperm proteingradually decreased from 7 to 30 DPA. Theseresults suggest a relatively active accumula-tion of this protein in young endosperms (7-DPA-old or younger). On the other hand,rapid accumulation of storage proteins did notoccur until 7 DPA. when ES-CBP had accu-mulated by a significant amount ES-CBPwas evidently degraded after 2 DPG (dayspost germination), and only trace amount ofthis lectin remained in 7-DPG endosperm.Such a pattern of accumulation and degrada-tion of ES-CBP is in favor of the hynothesisthat it acts as an organizer of protein body inrice endosperm.