肌动蛋白，肌球蛋白以及肌联蛋白在肌肉的收缩过程中扮演着重要的角色，欧洲分子生物学实验室（EMBL）的科学家目前正在对另外一种肌肉蛋白-myomesin进行实验研究，这种蛋白可以拉长至自身长度的2.5倍，以一种前所未闻的方式进行展开，2月14日，相关的研究成果发表在了国际杂志PLoS Biology上。
myomesin连接着肌丝进行伸缩，所以说这种蛋白是很有弹性的，实验室的研究者Matthias Wilmanns和他的研究伙伴运用X-射线晶体学方法，X-射线散射方法，电镜及原子力显微镜检查等方法来揭示这种蛋白伸展能力的机制，研究者们通过大量实验发现，myomesin蛋白的拉伸部位就像是串联珍珠的细绳子，拉着免疫球蛋白结构域，就像我们知道的α-螺旋一样，将弹性带隔离在外。
当这种蛋白被拆解的时候，中间的单环会展开，然而免疫球蛋白结构域并不会展开，作者新的研究发现给科学界在免疫球蛋白结构域是否存在潜在的弹性提供了新的线索，下一步，Wilmanns教授将和他的研究团队将会研究myomesin蛋白在身体代谢中扮演的角色，并且确定这种蛋白如何和其它肌肉成分进行反应和交流的。（生物谷：T.Shen编译）
doi:10.1371/journal.pbio.1001261
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Superhelical Architecture of the Myosin Filament-Linking Protein Myomesin with Unusual Elastic Properties
Nikos Pinotsis1,2#¤, Spyros D. Chatziefthimiou1,3#, Felix Berkemeier4, Fabienne Beuron2, Irene M. Mavridis3, Petr V. Konarev1, Dmitri I. Svergun1, Edward Morris2, Matthias Rief4, Matthias Wilmanns1*
Active muscles generate substantial mechanical forces by the contraction/relaxation cycle, and, to maintain an ordered state, they require molecular structures of extraordinary stability. These forces are sensed and buffered by unusually long and elastic filament proteins with highly repetitive domain arrays. Members of the myomesin protein family function as molecular bridges that connect major filament systems in the central M-band of muscle sarcomeres, which is a central locus of passive stress sensing. To unravel the mechanism of molecular elasticity in such filament-connecting proteins, we have determined the overall architecture of the complete C-terminal immunoglobulin domain array of myomesin by X-ray crystallography, electron microscopy, solution X-ray scattering, and atomic force microscopy. Our data reveal a dimeric tail-to-tail filament structure of about 360 Å in length, which is folded into an irregular superhelical coil arrangement of almost identical α-helix/domain modules. The myomesin filament can be stretched to about 2.5-fold its original length by reversible unfolding of these linkers, a mechanism that to our knowledge has not been observed previously. Our data explain how myomesin could act as a highly elastic ribbon to maintain the overall structural organization of the sarcomeric M-band. In general terms, our data demonstrate how repetitive domain modules such as those found in myomesin could generate highly elastic protein structures in highly organized cell systems such as muscle sarcomeres.
