Hynes R O, Ali I U, Mautner V M, Destree A
Birth Defects Orig Artic Ser. 1978;14(2):139-53.
LETS is a large surface glycoprotein that is found on normal fibroblasts, but is absent or exists in amounts on transformed cells. Immunofluorescent staining shows LETS protein fibrils arrayed around the cells, particularly concentrated beneath the cells and in the area between neighboring cells. LETS glycoprotein is disulfide-bonded at the cell surface into dimers and higher aggregates. Other surface proteins also appear to participate in disulfide bonding. Reduction of disulfide bonds leads to increased release of LETS protein from the cells, as does the addition of cytochalasin B. Purified LETS protein added to transformed cells binds to the cells in a fibrillar array similar to that seen on normal cells. Addition of LETS protein leads to increased attachment and spreading of cells and causes transformed cells to align like normal ones. It also causes the appearance of actin cables in transformed cells, which normally lack them. These effects are inhibited by specific antisera to LETS protein or by reduction of disulfide bonds in the protein and are blocked or reversed by proteolysis. The results suggest that LETS protein plays a role in adhesion of cells.
LETS是一种大型表面糖蛋白，存在于正常成纤维细胞上，但在转化细胞中不存在或含量很低。免疫荧光染色显示LETS蛋白纤维排列在细胞周围，尤其集中在细胞下方和相邻细胞之间的区域。LETS糖蛋白在细胞表面通过二硫键结合形成二聚体和更高的聚集体。其他表面蛋白似乎也参与二硫键结合。二硫键的还原会导致LETS蛋白从细胞中释放增加，细胞松弛素B的添加也会如此。添加到转化细胞中的纯化LETS蛋白以类似于正常细胞上所见的纤维状排列与细胞结合。LETS蛋白的添加会导致细胞附着和铺展增加，并使转化细胞像正常细胞一样排列。它还会使通常缺乏肌动蛋白索的转化细胞出现肌动蛋白索。这些作用被针对LETS蛋白的特异性抗血清或蛋白中二硫键的还原所抑制，并被蛋白水解阻断或逆转。结果表明LETS蛋白在细胞黏附中起作用。
