Baird W V, Meagher R B
Department of Genetics, University of Georgia, Athens 30602.
EMBO J. 1987 Nov;6(11):3223-31. doi: 10.1002/j.1460-2075.1987.tb02639.x.
We have shown by several independent criteria that actin is encoded by a very large and complex superfamily of genes in Petunia. Several cDNA and genomic probes encoding actins from diverse organisms (Dictyostelium, Drosophila, chicken and soybean) hybridize to hundreds of restriction fragments in the petunia genome. Actin-hybridizing sequences were isolated from a petunia genomic library at a rate of at least 200 per genome equivalent. Twenty randomly selected actin-hybridizing clones were characterized in more detail. DNA sequence data from four representative and highly divergent clones, PAc2, PAc3, PAc4 and PAc7, demonstrate that these actin-like sequences are related to functional actin genes. Intron positions typical of other known plant actin genes are conserved in these clones. Four of six clones analyzed (PAc1, PAc2, PAc3, PAc4) hybridize to leaf mRNA of the same size (1.7 kb) as that reported for other plant actin mRNAs and to a slightly smaller mRNA species (1.5 kb). Five distinct subfamilies of actin-related genes were characterized which varied in size from a few members to several dozen members. It is clear from our data that other actin gene subfamilies must also exist within the genome. Possible mechanisms of actin gene amplification and genome turnover are discussed.
我们已经通过多种独立标准证明，矮牵牛中的肌动蛋白由一个非常庞大且复杂的基因超家族编码。几个编码来自不同生物体（盘基网柄菌、果蝇、鸡和大豆）肌动蛋白的cDNA和基因组探针与矮牵牛基因组中的数百个限制性片段杂交。从矮牵牛基因组文库中分离出肌动蛋白杂交序列，其速率至少为每个基因组当量200个。对20个随机选择的肌动蛋白杂交克隆进行了更详细的表征。来自四个代表性且差异很大的克隆PAc2、PAc3、PAc4和PAc7的DNA序列数据表明，这些肌动蛋白样序列与功能性肌动蛋白基因相关。这些克隆中保留了其他已知植物肌动蛋白基因典型的内含子位置。分析的六个克隆中的四个（PAc1、PAc2、PAc3、PAc4）与大小与其他植物肌动蛋白mRNA相同（1.7 kb）的叶片mRNA杂交，并与一个稍小的mRNA种类（1.5 kb）杂交。鉴定出了五个不同的肌动蛋白相关基因亚家族，其大小从几个成员到几十个成员不等。从我们的数据可以清楚地看出，基因组中肯定还存在其他肌动蛋白基因亚家族。文中还讨论了肌动蛋白基因扩增和基因组更新的可能机制。
