Direct binding of nuclear membrane protein MAN1 to emerin in vitro and two modes of binding to barrier-to-autointegration factor
Direct binding of nuclear membrane protein MAN1 to emerin in vitro and two modes of binding to barrier-to-autointegration factor
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DOI：
10.1074/jbc.m413020200
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发表时间：
2005-04-08
影响因子：
4.8
通讯作者：
Wilson, KL
中科院分区：
文献类型：
--
作者：
Mansharamani, M;Wilson, KL
MAN1 是一种脊椎动物核内膜蛋白，可抑制转化生长因子 β 下游的 Smad 信号传导。 MAN1具有暴露的含有LEM结构域的N端区域（“MAN1-N”）、两个跨膜结构域和暴露的C端结构域（“MAN1-C”）。人类 MAN1 的许多区域与 emerin 同源，emerin 是一种 LEM 结构域核蛋白，其缺失会导致 Emery-Dreifuss 肌营养不良症 ( EDMD )。为了检验 MAN1 功能可能与 emerin 重叠的假设，我们测试了 MAN1 的不同多肽片段与 emerin 选定伴侣的结合。我们的研究结果支持这一假设。印迹重叠分析和免疫共沉淀研究表明 MAN1-C 结合转录调节因子 GCL、Btf 和自整合屏障因子 (BAF)。 BAF 与这个没有 LEM 结构域的区域的结合是值得注意的。序列比对鉴定出 MAN1-C 和其他两种 BAF 结合蛋白中潜在的 BAF 结合基序，其特征是保守残基 Ser-Arg-Val。另一个区域 MAN1-N 直接与 BAF、核纤层蛋白 A 和核纤层蛋白 B1 结合，支持与 emerin 的功能重叠。出乎意料的是，三项独立测定表明 MAN1-N 也直接与 emerin 结合。在 EDMD 疾病机制和潜在体内功能的背景下讨论了拟议的 MAN1-emerin 复合物。
MAN1 is a vertebrate nuclear inner membrane protein that inhibits Smad signaling downstream of transforming growth factor beta. MAN1 has an exposed LEM domain-containing N-terminal region ("MAN1-N"), two transmembrane domains, and an exposed C-terminal domain ("MAN1-C"). Many regions of human MAN1 are homologous to emerin, a LEM domain nuclear protein, loss of which causes Emery-Dreifuss muscular dystrophy ( EDMD). To test the hypothesis that MAN1 function might overlap with emerin, we tested different polypeptide fragments of MAN1 for binding to selected partners of emerin. Our findings support this hypothesis. Blot overlay assays and co-immunoprecipitation studies showed that MAN1-C binds the transcription regulators GCL, Btf, and barrier-to-autointegration factor (BAF). BAF binding to this region, which has no LEM domain, was notable. Sequence alignments identified a potential BAF-binding motif, characterized by the conserved residues Ser-Arg-Val, in MAN1-C and two other BAF-binding proteins. The other region, MAN1-N, bound directly to BAF, lamin A, and lamin B1, supporting functional overlap with emerin. Unexpectedly, three independent assays showed that MAN1-N also bound directly to emerin. Proposed MAN1-emerin complexes are discussed in the context of EDMD disease mechanisms and potential in vivo functions.