Dhugga K S, Tiwari S C, Ray P M
Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA.
Proc Natl Acad Sci U S A. 1997 Jul 8;94(14):7679-84. doi: 10.1073/pnas.94.14.7679.
We purified from pea (Pisum sativum) tissue an approximately 40 kDa reversibly glycosylated polypeptide (RGP1) that can be glycosylated by UDP-Glc, UDP-Xyl, or UDP-Gal, and isolated a cDNA encoding it, apparently derived from a single-copy gene (Rgp1). Its predicted translation product has 364 aminoacyl residues and molecular mass of 41.5 kDa. RGP1 appears to be a membrane-peripheral protein. Immunogold labeling localizes it specifically to trans-Golgi dictyosomal cisternae. Along with other evidence, this suggests that RGP1 is involved in synthesis of xyloglucan and possibly other hemicelluloses. Corn (Zea mays) contains a biochemically similar and structurally homologous RGP1, which has been thought (it now seems mistakenly) to function in starch synthesis. The expressed sequence database also reveals close homologs of pea Rgp1 in Arabidopsis and rice (Oryza sativa). Rice possesses, in addition, a distinct but homologous sequence (Rgp2). RGP1 provides a polypeptide marker for Golgi membranes that should be useful in plant membrane studies.
我们从豌豆（Pisum sativum）组织中纯化出一种约40 kDa的可逆糖基化多肽（RGP1），它可被UDP-葡萄糖、UDP-木糖或UDP-半乳糖糖基化，并分离出编码该多肽的cDNA，该cDNA显然来源于单拷贝基因（Rgp1）。其预测的翻译产物有364个氨酰基残基，分子量为41.5 kDa。RGP1似乎是一种膜周边蛋白。免疫金标记将其特异性定位在反式高尔基体的潴泡上。结合其他证据，这表明RGP1参与木葡聚糖以及可能其他半纤维素的合成。玉米（Zea mays）含有一种生化性质相似且结构同源的RGP1，人们曾认为（现在看来是错误的）它在淀粉合成中起作用。表达序列数据库还揭示了拟南芥和水稻（Oryza sativa）中与豌豆Rgp1密切同源的序列。此外，水稻还拥有一个独特但同源的序列（Rgp2）。RGP1为高尔基体膜提供了一种多肽标记物，这在植物膜研究中应该会很有用。
