Sobieszek A, Bremel R D
Eur J Biochem. 1975 Jun 16;55(1):49-60. doi: 10.1111/j.1432-1033.1975.tb02137.x.
A new technique for obtaining a myofibril-like preparation from vertebrate smooth muscle has been developed. An actomyosin can be readily extracted from these myofibrils at low ionic strength and in yields 20 times as high as previously reported. The protein composition of all preparations has been monitored using dodecylsulfate-gel electrophoresis. By this method smooth muscle actomyosin showed primarily only the major proteins, myosin, actin and tropomyosin, while the myofibrils contained, additionally, three new proteins not previously described with polypeptide chain weights of 60000, 110000 and 130000. The ATPase activities of both the myofibrils and actomyosin preparations are considerably higher than previously described for vertebrate smooth muscle. They are sensitive to micromolar Ca2+ ion concentrations to the same degree as comparable skeletal and cardiac muscle preparations, even though troponin-like proteins could not be identified in these smooth muscle preparations. From the latter observation and the presence of Ca2+-sensitivity in tropomyosin-free actomyosin it is suggested that this calcium sensitivity is, as in some invertebrate muscles, a property of the myosin molecule.
已开发出一种从脊椎动物平滑肌中获取肌原纤维样制剂的新技术。在低离子强度下，可轻松从这些肌原纤维中提取肌动球蛋白，其产量比先前报道的高20倍。使用十二烷基硫酸盐 - 凝胶电泳监测所有制剂的蛋白质组成。通过这种方法，平滑肌肌动球蛋白主要仅显示主要蛋白质，即肌球蛋白、肌动蛋白和原肌球蛋白，而肌原纤维还含有另外三种先前未描述的新蛋白质，其多肽链分子量分别为60000、110000和130000。肌原纤维制剂和肌动球蛋白制剂的ATP酶活性均明显高于先前对脊椎动物平滑肌的描述。它们对微摩尔浓度的Ca2+离子浓度敏感，程度与可比的骨骼肌和心肌制剂相同，尽管在这些平滑肌制剂中未鉴定出肌钙蛋白样蛋白质。根据后一观察结果以及在无原肌球蛋白的肌动球蛋白中存在Ca2+敏感性，表明这种钙敏感性如同在一些无脊椎动物肌肉中一样，是肌球蛋白分子的一种特性。
