KETTIN, A LARGE MODULAR PROTEIN IN THE Z-DISC OF INSECT MUSCLES
KETTIN, A LARGE MODULAR PROTEIN IN THE Z-DISC OF INSECT MUSCLES
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DOI：
10.1002/j.1460-2075.1993.tb05948.x
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发表时间：
1993-07-01
期刊：
影响因子：
11.4
通讯作者：
BULLARD, B
中科院分区：
文献类型：
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作者：
LAKEY, A;LABEIT, S;BULLARD, B
昆虫飞行肌的Z盘含有500-700 kDa的大蛋白质。单克隆抗体标记果蝇和Lethocerus（水蝽）Z盘分子中的表位。已从果蝇基因中克隆了1.6kb的部分cDNA并进行了序列测定。相应的氨基酸序列具有由与免疫球蛋白C2结构域（在肌肉蛋白中称为II类结构域）同源的95个氨基酸的四个保守重复序列组成的模块结构，其由35个氨基酸的较不保守的接头序列分开。 具有侧翼接头序列的表达的II类结构域结合肌动蛋白和α-辅肌动蛋白，但不结合肌球蛋白。蛋白质的单个分子将大到足以跨越Z盘。我们认为这种蛋白质在Z盘中起着支架的作用，我们称这种蛋白质为kettin。钙激活的蛋白酶，钙蛋白酶，破坏横纹肌的Z盘，释放α-辅肌动蛋白完整。钙蛋白酶将kettin降解为一系列从肌原纤维释放的30至170 kDa的肽。kettin的消化可引起Z盘的崩解和α-辅肌动蛋白的释放，这导致肌原纤维的分解。
Z-discs of insect flight muscle contain a large protein of 500-700 kDa. Monoclonal antibodies label an epitope in the molecule at the Z-disc in Drosophila and Lethocerus (waterbug). A partial cDNA of 1.6 kb from the Drosophila gene has been cloned and sequenced. The corresponding amino acid sequence has a modular structure composed of four conserved repeats of 95 amino acids homologous to immunoglobulin C2 domains (called class II domains in muscle proteins), separated by less conserved linker sequences of 35 amino acids. An expressed class II domain with flanking linker sequences binds to actin and alpha-actinin but not to myosin. Single molecules of the protein would be large enough to span the Z-disc. We suggest that the protein acts as scaffolding in the Z-disc and we call the protein kettin. The Ca2+ activated protease, calpain, disrupts the Z-disc of striated muscle, releasing alpha-actinin intact. Calpain digests kettin to a series of peptides of between 30 and 170 kDa which are released from the myofibril. Digestion of kettin may cause disintegration of the Z-disc and alpha-actinin release which lead to disassembly of the myofibril.