Kabat-Zinn J, Singer R H
J Cell Biol. 1981 Apr;89(1):109-14. doi: 10.1083/jcb.89.1.109.
Actin is the major extractable protein component from the tube feet of four different species of sea urchin: Arbacia punctulata, Strongylocentrotus purpuratus, Strongylocentrotus droebachiensis, and Diadema setosum. Actin made up as much as 60% of the total Coomassie Blue-staining material after SDS polyacrylamide gel electrophoresis and densitometer analysis. Two-dimensional gel electrophoresis resolved two, and possible three, species of actin for each sea urchin of which the dominant component was analogous to the beta form in vertebrates. In a cell-free system from rabbit reticulocytes, total RNA from tube feet stimulated the synthesis of one protein that represented 80% of the total methionine incorporation, migrated with the properties characteristic of actin in a two-dimensional gel system, and on proteolysis yielded fragments identical to purified rabbit actin. The mRNAs from the tube feet of two divergent species of sea urchin, Arbacia punctulata and Strongylocentrotus purpuratus, synthesized actins differing by less than 0.02 pH unit for each isospecies 90% of the DNA copied from tube foot RNA by reverse transcriptase represented a highly abundant sequence class judged by copy DNA(cDNA)-RNA excess hybridization. At least two-thirds of this class represented a low-complexity component, with a Rot1/2 about three times that expected for actin messenger RNA. The remarkable degree of conservation of the actin protein is reflected in concomitant conservation of the protein-coding nucleotide sequences of the messenger RNA, which has allowed the use of a cDNA probe to isolate actin sequences from a human phage library.
肌动蛋白是四种不同海胆（斑点海胆、紫海胆、球海胆和刺冠海胆）管足中主要的可提取蛋白质成分。经过十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳和密度计分析后，肌动蛋白占考马斯亮蓝染色物质总量的60%。双向凝胶电泳分离出每种海胆的两种，可能还有三种肌动蛋白，其中主要成分类似于脊椎动物中的β型。在兔网织红细胞的无细胞系统中，管足的总RNA刺激了一种蛋白质的合成，该蛋白质占总甲硫氨酸掺入量的80%，在双向凝胶系统中迁移时具有肌动蛋白的特征性质，并且经蛋白酶水解后产生与纯化的兔肌动蛋白相同的片段。两种不同海胆（斑点海胆和紫海胆）管足的mRNA合成的肌动蛋白，每种同型的差异小于0.02pH单位。通过逆转录酶从管足RNA复制的DNA中，90%代表了一种高度丰富的序列类别，这是通过cDNA - RNA过量杂交判断的。该类别中至少三分之二代表低复杂性成分，其Rot1/2约为肌动蛋白信使RNA预期值的三倍。肌动蛋白蛋白质的显著保守程度反映在信使RNA的蛋白质编码核苷酸序列的伴随保守上，这使得能够使用cDNA探针从人噬菌体文库中分离肌动蛋白序列。
