Melusin is a new muscle-specific interactor for β1 integrin cytoplasmic domain
Melusin is a new muscle-specific interactor for β1 integrin cytoplasmic domain
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DOI：
10.1074/jbc.274.41.29282
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发表时间：
1999-10-08
影响因子：
4.8
通讯作者：
Silengo, L
中科院分区：
文献类型：
--
作者：
Brancaccio, M;Guazzone, S;Silengo, L
在这里，我们描述了一种新的肌肉特异性蛋白质（Melusin）的分离和部分表征，它与整合素胞质结构域相互作用。在使用β（1）A和β（1）D整合素胞质区作为诱饵的大鼠新生心脏文库的双杂交筛选中分离编码Melusin的cDNA。Melusin是一种富含半胱氨酸的细胞质蛋白，分子量为38 kDa，在羧基末端有一段酸性氨基酸残基。此外，SH 3和SH 2结构域的推定结合位点存在于分子的氨基末端的一半。染色体分析表明，melusin基因在人中定位于Xq12.1/13，在小鼠中定位于染色体区域X带D。Melusin在骨骼肌和心肌中表达，但在平滑肌或其他组织中不表达。免疫荧光分析表明Melusin在Z线上以costamere样模式存在，由两排侧翼α-辅肌动蛋白组成，其表达在C2 C12小鼠肌源性细胞系的体外分化过程中上调，并且在体内骨骼肌发育过程中受到调节。Melusin的尾区片段与β 1整合素胞浆区有较强的特异性相互作用，而全长蛋白则无此作用。由于Melusin的尾部区域含有类似于高容量和低亲和力钙结合结构域的酸性氨基酸段，我们测试了Ca 2+调节Melusin-整联蛋白缔合的可能性。体外结合实验表明，全长Melusin与去污剂增溶的整合素异二聚体的相互作用仅在不存在阳离子的情况下发生，这表明它可以通过影响Ca 2+浓度的细胞内信号来调节。
Here we describe the isolation and partial characterization of a new muscle-specific protein (Melusin) which interacts with the integrin cytoplasmic domain. The cDNA encoding Melusin was isolated in a two-hybrid screening of a rat neonatal heart library using beta(1)A and beta(1)D integrin cytoplasmic regions as baits. Melusin is a cysteine-rich cytoplasmic protein of 38 kDa, with a stretch of acidic amino acid residues at the extreme carboxyl-terminal end. In addition, putative binding sites for SH3 and SH2 domains are present in the aminoterminal half of the molecule. Chromosomic analysis showed that melusin gene maps at Xq12.1/13 in man and in the synthenic region X band D in mouse. Melusin is expressed in skeletal and cardiac muscles but not in smooth muscles or other tissues. Immunofluorescence analysis showed that Melusin is present in a costamere-like pattern consisting of two rows flanking alpha-actinin at Z line, Its expression is up-regulated during in vitro differentiation of the C2C12 murine myogenic cell line, and it is regulated during in vivo skeletal muscle development. A fragment corresponding to the tail region of Melusin interacted strongly and specifically with beta(1) integrin cytoplasmic domain in a two-hybrid test, but the full-length protein did not. Because the tail region of Melusin contains an acidic amino acid stretch resembling high capacity and low affinity calcium binding domains, we tested the possibility that Ca2+ regulates Melusin-integrin association. In vitro binding experiments demonstrated that interaction of full-length Melusin with detergent-solubilized integrin heterodimers occurred only in absence of cations, suggesting that it can be regulated by intracellular signals affecting Ca2+ concentration.