Xu L, Gonzalez-Agosti C, Beauchamp R, Pinney D, Sterner C, Ramesh V
Molecular Neurogenetics Unit, Massachusetts General Hospital East, Charlestown 02129, USA.
Exp Cell Res. 1998 Jan 10;238(1):231-40. doi: 10.1006/excr.1997.3843.
The Neurofibromatosis 2 gene product, merlin, has striking similarity to ezrin, radixin, and moesin (ERM), members of the protein 4.1 family which have been demonstrated to connect proteins in the plasma membrane to the cytoskeletal components. The recent localization of merlin to the motile regions in cultured cells such as membrane ruffles further supports the notion that merlin represents a new class of tumor suppressors. Here we describe the localization of full-length and truncated polypeptides of merlin expressed as Flag-tagged proteins in transfected cells. Similar to endogenous merlin, the epitope-tagged full-length merlin localizes to the membrane ruffles in transfected Cos-7 cells and rat Schwann cells. In addition, the over-expressed merlin localizes to other actin-rich cortical structures, such as microvilli and filopodia. The amino-terminal half of merlin is seen dispersed throughout the cells and in membrane ruffles. Compared to the amino-terminal half of merlin, its carboxy-terminal half localizes more distinctly to membrane ruffles. The full-length and the carboxy-terminal portion of merlin co-localize with F-actin at the membrane ruffles. However, distinct from the ERM proteins, the carboxy-terminal-truncated merlin and F-actin do not co-localize with each other at the stress fibers. Our results suggest that both the amino- and the carboxy-terminal domains of merlin contribute to its membrane ruffle localization.
神经纤维瘤病2基因产物merlin与埃兹蛋白、根蛋白和膜突蛋白（ERM）具有显著相似性，它们是蛋白质4.1家族的成员，已被证明能将质膜中的蛋白质与细胞骨架成分相连。最近在培养细胞（如膜皱褶）的运动区域发现merlin的定位，进一步支持了merlin代表一类新的肿瘤抑制因子的观点。在此，我们描述了在转染细胞中作为Flag标签蛋白表达的merlin全长和截短多肽的定位。与内源性merlin相似，表位标签的全长merlin定位于转染的Cos-7细胞和大鼠雪旺细胞的膜皱褶处。此外，过表达的merlin定位于其他富含肌动蛋白的皮质结构，如微绒毛和丝状伪足。merlin的氨基末端一半分散在整个细胞和膜皱褶中。与merlin的氨基末端一半相比，其羧基末端一半更明显地定位于膜皱褶处。merlin的全长和羧基末端部分在膜皱褶处与F-肌动蛋白共定位。然而，与ERM蛋白不同，羧基末端截短的merlin和F-肌动蛋白在应力纤维处不相互共定位。我们的结果表明，merlin的氨基末端和羧基末端结构域都有助于其在膜皱褶处的定位。
