Keicher Christian, Gambaryan Stepan, Schulze Elfriede, Marcus Katrin, Meyer Helmut E, Butt Elke
Institute of Clinical Biochemistry and Pathobiochemistry, University of Würzburg, Josef-Schneider-Str. 2, D-97080 Würzburg, Germany.
Biochem Biophys Res Commun. 2004 Nov 5;324(1):308-16. doi: 10.1016/j.bbrc.2004.08.235.
LIM and SH3 domain protein (LASP-1) is a specific focal adhesion protein involved in cell migration. Overlay studies demonstrate that LASP-1 directly binds to the proline-rich domains of zyxin, lipoma preferred partner (LPP), and vasodilator-stimulated phosphoprotein (VASP), with zyxin being the most prominent interacting partner. Despite the LIM/zinc-finger domain, hypothesized to be involved in homodimerization, LASP-1 exists as a monomer. In vitro phosphorylation of recombinant mouse LASP-1 by cAMP- and cGMP-dependent protein kinase (PKA and PKG, respectively) occurs at serine 61, serine 99, and threonine 156 whereas in intact cells mouse LASP-1 is phosphorylated only at threonine 156. This site is different from the known in vivo phosphorylation sites in human (serine 146) and rabbit (serine 99 and serine 146). Nevertheless, immunofluorescence of LASP-1 in human and mouse mesangial cells revealed no difference in subcellular distribution. Exposure of the cells to forskolin induced a translocation of both, human and mouse LASP-1, from the focal contacts to the cell interior without affecting F-actin structure. Immunoblotting of LASP-1 in various mouse and human tissues detected a similar prominent expression in non-muscle tissue. Altogether, our data suggest so far no functional differences between human and mouse LASP-1.
LIM和SH3结构域蛋白（LASP-1）是一种参与细胞迁移的特异性粘着斑蛋白。覆盖实验表明，LASP-1直接与桩蛋白、脂肪瘤优先结合蛋白（LPP）和血管舒张刺激磷蛋白（VASP）富含脯氨酸的结构域结合，其中桩蛋白是最主要的相互作用伴侣。尽管推测LIM/锌指结构域参与同源二聚化，但LASP-1以单体形式存在。重组小鼠LASP-1分别被cAMP和cGMP依赖性蛋白激酶（分别为PKA和PKG）在体外磷酸化的位点为丝氨酸61、丝氨酸99和苏氨酸156，而在完整细胞中，小鼠LASP-1仅在苏氨酸156处被磷酸化。该位点与人类（丝氨酸146）和兔子（丝氨酸99和丝氨酸146）已知的体内磷酸化位点不同。然而，人及小鼠系膜细胞中LASP-1的免疫荧光显示亚细胞分布无差异。用福斯可林处理细胞会导致人及小鼠LASP-1从粘着斑向细胞内部移位，而不影响F-肌动蛋白结构。对各种小鼠和人类组织中LASP-1的免疫印迹检测发现，其在非肌肉组织中的表达同样显著。总之，我们的数据目前表明人及小鼠LASP-1之间没有功能差异。
