论文部分内容阅读
在巴西橡胶树中，乳管里的橡胶粒子是橡胶（顺式１，４—聚异戊二烯）生物合成的场所。橡胶延长因子（ＲＥＦ）这种１４千道尔顿的蛋白质与橡胶分子按１：１在橡胶粒子上结合。为了获得更多有关ＲＥＦ的功能及其在橡胶粒子中的合成、装配等方面的信息，我们分离了编码ＲＥＦ的ｃＤＮＡ克隆。我们利用ＲＥＦ的抗体对橡胶叶片λｇｔ１１ｃＤＮＡ表达文库进行筛选并获得几个阳性克隆。对ＲＥＦｃＤＮＡ克隆的序列分析表明，ＲＥＦｍＲＮＡ含有一个具１２１个核苷酸的５′端非转译序列及一个具２０５个核苷酸的３′端非转译区段。开放阅读框编码完整的１４千道尔顿ＲＥＦ蛋白质，不带任何额外的氨基酸。ＲＥＦｃＤＮＡ在ｐＧＥＭ—３Ｚ／－４Ｚ中作亚克隆并进行体外表达，其翻译产物是一种１４千道尔顿的蛋白质，该蛋白质可与ＲＥＦ的相应抗体发生免疫沉淀反应。于体外翻译产物中加入微粒体膜不改变该ＲＥＦ蛋白质的迁移率。以上结果和序列数据说明，ＲＥＦ不是以前蛋白质的形式合成的。我们的结果表明，ＲＥＦ是在乳管细胞质中的游离多核糖体上合成的，而橡胶粒子的装配则很可能发生在胞液中。
In the Brazilian rubber tree, the rubber particles in the tube are where the rubber (cis 1,4-polyisoprene) biosynthesizes. Rubber Stretch Factor (REF) This 14 kiloDalton protein binds rubber molecules at 1: 1 on rubber particles. To obtain more information about REF’s function and its synthesis, assembly, etc. in rubber particles, we isolated the cDNA clone encoding REF. We screened rubber leaf λgt11 cDNA expression libraries using antibodies to REF and obtained several positive clones. Sequence analysis of the REFcDNA clone showed that the REF mRNA contains a 5 ’untranslated sequence of 121 nucleotides and a 3’ untranslated segment of 205 nucleotides. The open reading frame encodes a complete 14 kilodalton REF protein without any additional amino acids. REFcDNA was subcloned in pGEM-3Z / -4Z and expressed in vitro. The translation product was a 14 kilodalton protein that immunoprecipitated with the corresponding antibody of REF. The addition of microsomal membranes to in vitro translation products did not alter the mobility of the REF protein. The above results and sequence data indicate that REF is not synthesized as a previous protein. Our results show that REF is synthesized on the free polysome in the cytoplasm of the ductal tube, whereas assembly of rubber particles is most likely to occur in the cytosol.