Abstract:

The molecular structure of a higher plant myosin with two 174 kD heavy chains purified from the tendrils of Luffa cylindrica(L.) Roem. was viewed by electron microscopy. The myosin exhibited actin-activated MgATPase activity and could be recognized immunologically by a monoclonal antibody against the skeletal muscle myosin. Electron micrographs of rotary shadowed images of this protein revealed that it had two heads with size and shape similar to those of the skeletal muscle myosin and a relatively short tail in comparison with the conventional myosin. Luffa tendril actin filaments were also visualized and occasionally other Luffa myosin-like proteins with globular structure at the tail ends were also observed. The structural similarity and immunological cross reactivity with antibodies against muscle myosin demonstrate that the 174 kD Luffa tendril myosin is a double-headed myosin. The possible involvement of myosin-actin interactions in Luffa tendril contact coiling will be the subject of further research.

丝瓜肌球蛋白的电子显微学研究

赵发清¹ 阎隆飞²

(1. 南昌大学生物学系,南昌 330047；2. 中国农业大学生物学院,北京100094)

摘要：从丝瓜(Luffa cylindrica (L.) Roem.)卷须中纯化得到分子量为174kD的肌球蛋白,并对其进行了酶学与电子显微学的研究.这种肌球蛋白具有肌动蛋白激活的MgATPase活性,能够被抗动物肌肉的肌球蛋白的单克隆抗体识别.电子显微学研究表明:它有两个头部(大小和形状与动物肌肉的肌球蛋白相似)和一条相对较短的尾部.还对丝瓜卷须的肌动蛋白进行了观测,偶尔发现一些尾部有球状结构的肌球蛋白.该肌球蛋白的免疫特性和超微结构证明了它由2条重链组成,并与传统的肌球蛋白相似.然而,这种174 kD的肌球蛋白是否参与了丝瓜的接触卷曲有待于进一步研究.

关键词 肌球蛋白 结构 电子显微学 纯化 丝瓜

Key words: myosin, structure, electron microscopy, purification, Luffa cylindrical