School of Plant Sciences, University of Reading, Reading, Berkshire, RG6 2AS, United Kingdom.
Plant Physiol. 1992 Jul;99(3):864-71. doi: 10.1104/pp.99.3.864.
We have examined the characteristics of Ca(2+)-dependent phospholipid-binding proteins (annexins) in maize (Zea mays L.) coleoptiles and tip-growing pollen tubes of Lilium longiflorum. In maize, there are three such proteins, p35, p33, and p23. Partial sequence analysis reveals that peptides from p35 and p33 have identity to members of the annexin family of animal proteins and to annexins from tomato. Interestingly, multiple sequence alignments reveal that the domain responsible for Ca(2+) binding in animal annexins is not conserved in these plant peptide sequences. Although p33 and p35 share the annexin characteristic of binding to membrane lipid, unlike annexins II and VI they do not associate with detergent-insoluble cytoskeletal proteins or with F-actin from either plants or animals. Immunoblotting with antiserum raised to p33/p35 from maize reveals that cross-reactive polypeptides of 33 to 35 kilodaltons are also present in protein extracts from pollen tubes of L. longiflorum. Immunolocalization at the light microscope level suggests that these proteins are predominantly confined to the nongranular zone at the tube tip, a region rich in secretory vesicles. Our hypothesis that plant annexins mediate exocytotic events is supported by the finding that p23, p33, and p35 bind to these secretory vesicles in a Ca(2+)-dependent manner.
我们研究了依赖 Ca2+的磷脂结合蛋白（膜联蛋白）在玉米（Zea mays L.）幼叶和百合（Lilium longiflorum）顶端生长花粉管中的特性。在玉米中，有三种这样的蛋白，p35、p33 和 p23。部分序列分析表明，p35 和 p33 的肽段与动物蛋白膜联蛋白家族的成员以及番茄中的膜联蛋白具有同源性。有趣的是，多重序列比对显示，动物膜联蛋白中负责结合 Ca2+的结构域在这些植物肽序列中并不保守。尽管 p33 和 p35 具有与膜脂结合的膜联蛋白特征，但与膜联蛋白 II 和 VI 不同，它们不与去污剂不溶性细胞骨架蛋白或来自植物或动物的 F-肌动蛋白结合。用针对玉米 p33/p35 的抗血清进行免疫印迹显示，百合花粉管蛋白提取物中也存在 33 至 35 千道尔顿的交叉反应性多肤。在光镜水平的免疫定位表明，这些蛋白主要局限于管尖的非颗粒区，这一区域富含分泌小泡。我们的假设是，植物膜联蛋白介导胞吐事件，这一假设得到了支持，即 p23、p33 和 p35 以 Ca2+依赖的方式与这些分泌小泡结合。
