Fujinoki Masakatsu, Tomiyama Toshiko, Ishimoda-Takagi Tadashi
Department of Biology, Tokyo Gakugei University, Koganei,Tokyo 184-8501, Japan.
J Exp Zool. 2002 Dec 1;293(7):649-63. doi: 10.1002/jez.10180.
Five isoforms of tropomyosin, designated as TMa, TMb, TMc, TMd, and TMe, were detected in the sea anemone, Anthopleura japonica. The apparent molecular weights of these isoforms were estimated to be approximately 30 kD to 37.5 kD, and their pI values were approximately 4.55 (TMa and TMb) and 4.65 (TMc, TMd, and TMe). Although sea anemone tropomyosin isoforms have the ability to bind to rabbit skeletal muscle actin, they preferably bind to actin at higher concentrations of Mg(2+) (10-20 mM) and slightly lower pH (6.2-7.2) than those used in conventional conditions. Antigenic properties of sea anemone tropomyosin seemed to be considerably specific to each isoform. Distribution of tropomyosin isoforms in the sea anemone body was somewhat portion-specific. TMa, TMb, and TMe were detected similarly in the extracts from tentacle, oral disc, column, mouth, and pedal disc. Although TMc and TMd were detected abundantly in the tentacle extract and moderately in the column and mouth extracts, these components were not contained in the pedal disc extract and detected only faintly in the oral disc extract.
在海葵日本拟花海葵（Anthopleura japonica）中检测到了五种原肌球蛋白亚型，分别命名为TMa、TMb、TMc、TMd和TMe。这些亚型的表观分子量估计约为30 kD至37.5 kD，其pI值分别约为4.55（TMa和TMb）以及4.65（TMc、TMd和TMe）。尽管海葵原肌球蛋白亚型能够与兔骨骼肌肌动蛋白结合，但与传统条件相比，它们更倾向于在较高浓度的Mg(2+)（10 - 20 mM）和略低的pH值（6.2 - 7.2）下与肌动蛋白结合。海葵原肌球蛋白的抗原特性似乎对每种亚型都具有相当的特异性。海葵体内原肌球蛋白亚型的分布在一定程度上具有部位特异性。在触手、口盘、柱体、口和足盘的提取物中，TMa、TMb和TMe的检测情况相似。尽管TMc和TMd在触手提取物中大量检测到，在柱体和口提取物中中度检测到，但在足盘提取物中未检测到这些成分，在口盘提取物中仅微弱检测到。
