McLean B G, Huang S R, McKinney E C, Meagher R B
Department of Genetics, University of Georgia, Athens 30602.
Cell Motil Cytoskeleton. 1990;17(4):276-90. doi: 10.1002/cm.970170403.
Actin protein isovariants have been identified in animals with distinct cytoplasmic or muscle specific patterns of expression. Analysis of vascular plant actin gene sequences suggests that an even greater diversity should exist within the plant actin protein families, but previous studies on plant proteins have not demonstrated the presence of multiple actin isovariants. Antibodies recognizing a conserved amino-terminal plant actin peptide, a family of plant actin peptides from a variable region, and two monoclonal antibodies to conserved epitopes within animal actins were used to identify isovariants of soybean actin resolved by two-dimensional isoelectric focusing (IEF) sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Approximately six to eight actin isovariants with pI values ranging from 5.1 to 5.8 have been identified from soybean hypocotyls, stems, leaves, and roots with varying amounts of most isovariants present in all four organs. Acidic isovariants were present in much higher levels in leaves and stems. Antisera with lambda-class actin specificity detected a subset of three isovariants in all organs examined. One monoclonal and one antipeptide antisera are shown to react well with a wide variety of plant actin isovariants. Similar patterns of actin isovariants were detected in the distant angiosperms, Arabidopsis, petunia, and maize. It is likely that many of these diverse classes of isovariants have been preserved throughout vascular plant evolution and reflect the ancient diversity within plant actin gene families. The extreme difference among isovariants implies the presence of a complex actin-based cytoskeletal system in plants.
在动物中已鉴定出具有不同细胞质或肌肉特异性表达模式的肌动蛋白同工型。对维管植物肌动蛋白基因序列的分析表明，植物肌动蛋白蛋白家族中应该存在更大的多样性，但先前对植物蛋白的研究尚未证明存在多种肌动蛋白同工型。使用识别保守氨基末端植物肌动蛋白肽、可变区的一组植物肌动蛋白肽以及针对动物肌动蛋白中保守表位的两种单克隆抗体，来鉴定通过二维等电聚焦（IEF）-十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）分离的大豆肌动蛋白同工型。从大豆下胚轴、茎、叶和根中已鉴定出大约6至8种等电点值在5.1至5.8之间的肌动蛋白同工型，所有四个器官中大多数同工型的含量各不相同。酸性同工型在叶和茎中的含量要高得多。具有λ类肌动蛋白特异性的抗血清在所有检测的器官中检测到三种同工型的一个子集。一种单克隆抗体和一种抗肽抗血清与多种植物肌动蛋白同工型反应良好。在远缘被子植物拟南芥、矮牵牛和玉米中检测到类似的肌动蛋白同工型模式。很可能这些不同类别的同工型中有许多在整个维管植物进化过程中得以保留，并反映了植物肌动蛋白基因家族中的古老多样性。同工型之间的极端差异意味着植物中存在复杂的基于肌动蛋白的细胞骨架系统。
