Molecular identification and comparison of the starch synthase bound to starch granules between endosperm and leaf blades in rice plants
Molecular identification and comparison of the starch synthase bound to starch granules between endosperm and leaf blades in rice plants
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水稻胚乳和叶片淀粉粒结合淀粉合酶的分子鉴定和比较
DOI：
10.1007/bf00554138
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发表时间：
1991
影响因子：
2.4
通讯作者：
T. Morikawa
中科院分区：
文献类型：
--
作者：
T. Taira;M. Uematsu;Y. Nakano;T. Morikawa
正常水稻（Oryza sativa和O. glaberrima）在胚乳淀粉中含有超过18%的直链淀粉，而蜡质（粘性）植物在这种淀粉中缺乏直链淀粉。与此相反，即使在蜡质植物中，叶淀粉也含有3.6%以上的直链淀粉。SDS-聚丙烯酰胺凝胶电泳分析表明，正常植株胚乳淀粉粒结合蛋白质只有一条带，分子量约为60 kd，而蜡质植株则没有类似的带。淀粉合成酶（NDP-葡萄糖-淀粉葡萄糖基转移酶）的活性被抗60-kd蛋白的抗体完全抑制。因此，我们认为60 kd蛋白是Wx等位基因编码的蜡质蛋白，它也参与胚乳组织中非淀粉的合成。叶片中淀粉粒结合蛋白在SDS-PAGE上分为5条带，分子量为53.6 ~ 64.9kd。用抗Wx蛋白的抗血清对这些蛋白进行免疫印迹分析，并用合成酶抗体抑制淀粉合成酶活性，结果表明这些蛋白均与Wx蛋白不同源。我们认为叶片中直链淀粉的合成是由一个不同于胚乳中表达的Wx基因的基因编码的蛋白质引起的。
Normal (nonglutinous) rice plants (Oryza sativaandO. glaberrima) contain more than 18% amylose in endosperm starch, whilewaxy(glutinous) plants lack it in this starch. In contrast, leaf starch contained more than 3.6% amylose even inwaxyplants. SDS-PAGE analysis of proteins bound to endosperm starch granules in the normal plants revealed a single band with aMrof 60 kd, whereaswaxyplants did not exhibit a similar band. The activity of starch synthase (NDP-glucose-starch glucosyltransferase) was completely inhibited by antibody against the 60-kd protein. Thus, we conclude that the 60-kd protein is thewaxyprotein encoded by theWxallele, which also plays a role in the synthesis of nonglutinous starch in endosperm tissue. In leaf blades, the proteins bound to starch granules separated into five bands withMr's of 53.6 to 64.9 kd on SDS-PAGE. Analysis of these proteins by immunoblotting using antiserum againstWxprotein and inhibition of starch synthase activity by the synthase antibody revealed that none of these proteins was homologous toWxprotein. We suggest that the synthesis of amylose in leaf blades is brought about by a protein encoded by a gene(s) different from theWxgene expressed in the endosperm.