Immunoglobulin-like modules from titin I-band: Extensible components of muscle elasticity
Immunoglobulin-like modules from titin I-band: Extensible components of muscle elasticity
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DOI：
10.1016/s0969-2126(96)00036-6
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发表时间：
1996-03-15
期刊：
影响因子：
5.7
通讯作者：
Pastore, A
中科院分区：
文献类型：
--
作者：
Improta, S;Politou, AS;Pastore, A
背景资料：肌联蛋白是一种巨大的肌蛋白，它形成一条横跨肌节一半的肌丝，沿着它的长度具有多种功能。肌联蛋白位于肌节I带的区域被认为在肌肉的伸展性和被动弹性中起主要作用。在I带中，肌联蛋白序列主要由串联免疫球蛋白样（IG）模块的重复基序组成，插入潜在的非球状区域。高度重复的肌联蛋白架构表明，其机械性能的分子基础接近通过I-带和它们的接口的隔离组件的特性。本文报道了一个代表性的I带IG模块（127）在溶液中的结构测定，结果：127的结构由两个四链片（ABED和A 'GFC）组成的β三明治结构组成。该折叠属于免疫球蛋白超家族的中间框架（I框架），127与来自位于M线（M5）中的区域的另一个肌联蛋白模块的比较显示，127中的两个环（在B和C以及F和G链之间）较短，从而赋予该结构较不细长的外观。这种特征是特异性的IG结构域的I带，因此可能与该区域的蛋白质的功能。串联IG域的结构为蓝本，从127表明铰链区连接连续modules.Conclusions的存在：我们建议，肌联蛋白IG域的I带功能作为可扩展的组件肌肉弹性拉伸铰链区。
Background: The giant muscle protein titin forms a filament which spans half of the sarcomere and performs, along its length, quite diverse functions, The region of titin located in the sarcomere I-band is believed to play a major role in extensibility and passive elasticity of muscle. In the I-band, the titin sequence consists mostly of repetitive motifs of tandem immunoglobulin-like (Ig) modules intercalated by a potentially non-globular region. The highly repetitive titin architecture suggests that the molecular basis of its mechanical properties be approached through the characterization of the isolated components of the I-band and their interfaces. In the present paper, we report on the structure determination in solution of a representative Ig module from the I-band (127) as solved by NMR techniques.Results: The structure of 127 consists of a beta sandwich formed by two four-stranded sheets (named ABED and A'GFC). This fold belongs to the intermediate frame (I frame) of the immunoglobulin superfamily, Comparison of 127 with another titin module from the region located in the M-line (M5) shows that two loops (between the B and C and the F and G strands) are shorter in 127, conferring a less elongated appearance to this structure. Such a feature is specific to the Ig domains in the I-band and might therefore be related to the functions of the protein in this region. The structure of tandem Ig domains as modeled from 127 suggests the presence of hinge regions connecting contiguous modules.Conclusions: We suggest that titin Ig domains in the I-band function as extensible components of muscle elasticity by stretching the hinge regions.