Small espin: a third actin-bundling protein and potential forked protein ortholog in brush border microvilli.
Small espin: a third actin-bundling protein and potential forked protein ortholog in brush border microvilli.
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DOI：
10.1083/jcb.143.1.107
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发表时间：
1998-10-05
影响因子：
7.8
通讯作者：
Chen, B
中科院分区：
文献类型：
--
作者：
Bartles, J R;Zheng, L;Li, A;Wierda, A;Chen, B
在大鼠肠和肾脏吸收上皮细胞刷状缘中发现了肌动蛋白结合/成束蛋白espin的约30 kD亚型。小espin在序列上与在支持细胞-精子细胞连接斑的肌动蛋白束中鉴定的较大（约110-kD）espin同种型的COOH末端相同（Bartles，J.R.，A. Wierda和L.郑1996.《细胞科学杂志》109：1229-1239），但其在其NH 2末端含有两个独特的肽。小espin定位于刷状缘微绒毛的平行肌动蛋白束，抵抗Triton X-100的提取，并在肠上皮细胞分化/迁移过程中沿沿着隐窝绒毛轴在成人的刷状缘积累。在转染的BHK成纤维细胞中，绿色荧光蛋白-小espin装饰含F-肌动蛋白的纤维，并似乎引起它们的积累和/或捆绑。重组小espin绑定到骨骼肌和非肌肉F-肌动蛋白具有高亲和力（Kd = 150和50 nM）和交联成束的细丝。沉淀、凝胶过滤和圆二色性分析表明，重组小espin是一种具有不对称形状和高百分比α-螺旋的单体。缺失突变表明，小espin包含两个肌动蛋白结合位点在其COOH端的116个氨基酸的肽和其分叉的同源肽的NH 2端的一半是必要的捆绑活动。
An ∼30-kD isoform of the actin-binding/ bundling protein espin has been discovered in the brush borders of absorptive epithelial cells in rat intestine and kidney. Small espin is identical in sequence to the COOH terminus of the larger (∼110-kD) espin isoform identified in the actin bundles of Sertoli cell–spermatid junctional plaques (Bartles, J.R., A. Wierda, and L. Zheng. 1996. J. Cell Sci. 109:1229–1239), but it contains two unique peptides at its NH2 terminus. Small espin was localized to the parallel actin bundles of brush border microvilli, resisted extraction with Triton X-100, and accumulated in the brush border during enterocyte differentiation/migration along the crypt–villus axis in adults. In transfected BHK fibroblasts, green fluorescent protein–small espin decorated F-actin–containing fibers and appeared to elicit their accumulation and/or bundling. Recombinant small espin bound to skeletal muscle and nonmuscle F-actin with high affinity (K d = 150 and 50 nM) and cross-linked the filaments into bundles. Sedimentation, gel filtration, and circular dichroism analyses suggested that recombinant small espin was a monomer with an asymmetrical shape and a high percentage of α-helix. Deletion mutagenesis suggested that small espin contained two actin-binding sites in its COOH-terminal 116–amino acid peptide and that the NH2-terminal half of its forked homology peptide was necessary for bundling activity.