Hitchcock-DeGregori S E, An Y
Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
J Biol Chem. 1996 Feb 16;271(7):3600-3. doi: 10.1074/jbc.271.7.3600.
Tropomyosin is a coiled-coil protein that binds along the length of filamentous actin and contains sequence repeats that correspond to actin monomers in the filament. Analysis of striated muscle alpha-tropomyosin mutants in which internal sequence has been deleted or replaced with non-tropomyosin sequence showed that the following parameters are important for high affinity, cooperative binding of tropomyosin-troponin to actin. 1) Tropomyosin must be a coiled coil along its entire length. 2) An integral number of repeats corresponding to the actin monomers along its length is more important than the total number. 3) In comparison, the actin affinity is relatively insensitive to changes in the sequence of the internal regions of tropomyosin. The results suggest that the internal sequence repeats function as weakly interacting spacers to allow proper alignment of the ends on the regulated actin filament.
原肌球蛋白是一种卷曲螺旋蛋白，它沿着丝状肌动蛋白的长度结合，并含有与细丝中的肌动蛋白单体相对应的序列重复。对横纹肌α-原肌球蛋白突变体的分析表明，其中内部序列已被删除或被非原肌球蛋白序列取代，以下参数对于原肌球蛋白-肌钙蛋白与肌动蛋白的高亲和力、协同结合很重要。1）原肌球蛋白在其整个长度上必须是卷曲螺旋。2）沿其长度与肌动蛋白单体相对应的重复序列的整数比总数更重要。3）相比之下，肌动蛋白亲和力对原肌球蛋白内部区域序列的变化相对不敏感。结果表明，内部序列重复起到弱相互作用间隔物的作用，以使末端在受调节的肌动蛋白丝上正确排列。
