Itoh Y, Suzuki T, Kimura S, Ohashi K, Higuchi H, Sawada H, Shimizu T, Shibata M, Maruyama K
Department of Biology, Faculty of Science, Chiba University.
J Biochem. 1988 Oct;104(4):504-8. doi: 10.1093/oxfordjournals.jbchem.a122499.
Two kinds of monoclonal antibodies (3B9 and SM1) against connectin, muscle elastic protein, reacted with both alpha- and beta-connectins. Immunofluorescence studies revealed that 3B9 stained both edges of the A band of chicken breast muscle myofibrils and remained as such upon stretching to a sarcomere length of 3.5 microns. On the other hand, SM1 stained the I band very close to the edges of the A band and the SM1-stained stripes moved considerably upon stretching to a sarcomere length of 3.5 microns. Immunoelectron microscopic observations with frog semitendinosus muscle revealed that three distinct stripes bound with 3B9 in the edges of the A band did not move on stretching up to 3.5 microns. On the other hand, the two stripes stained with SM1 in the I band clearly moved to the same extent as the stretching. However, when a sarcomere was stretched to 4.0 microns, all the stripes with 3B9 or SM1 disappeared and diffused deposits of the antibodies were observed. Thus it is concluded that connectin filaments in the I band region are more extensible than those at both edges of the A band.
两种针对连接蛋白（肌肉弹性蛋白）的单克隆抗体（3B9和SM1）与α-连接蛋白和β-连接蛋白均发生反应。免疫荧光研究显示，3B9对鸡胸肌肌原纤维A带的两边进行染色，并且在拉伸至肌节长度为3.5微米时仍保持这种状态。另一方面，SM1对非常靠近A带边缘的I带进行染色，并且在拉伸至肌节长度为3.5微米时，SM1染色的条纹发生了相当大的移动。对青蛙半腱肌进行免疫电子显微镜观察发现，在A带边缘与3B9结合的三条不同条纹在拉伸至3.5微米时并未移动。另一方面，I带中被SM1染色的两条条纹明显与拉伸程度同步移动。然而，当肌节拉伸至4.0微米时，所有带有3B9或SM1的条纹均消失，并观察到抗体的弥散性沉积。因此得出结论，I带区域的连接蛋白丝比A带两边的连接蛋白丝更具延展性。
