Wojcikiewicz Ewa P, Abdulreda Midhat H, Zhang Xiaohui, Moy Vincent T
Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, Florida 33136, USA.
Biomacromolecules. 2006 Nov;7(11):3188-95. doi: 10.1021/bm060559c.
Single-molecule measurements of the interaction of leukocyte function-associated antigen-1 (LFA-1), expressed on Jurkat T cells, with intercellular adhesion molecules-1 and -2 (ICAM-1 and ICAM-2) were conducted using atomic force microscopy (AFM). The force spectra (i.e., unbinding force versus loading rate) of both the LFA-1/ICAM-1 and LFA-1/ICAM-2 interactions were acquired at a loading rate range covering 3 orders of magnitude (50-60,000 pN/s) and revealed a fast loading regime and a slow loading regime. This indicates that the dissociation of both complexes involves overcoming a steep inner and a wide outer activation barrier. LFA-1 binding to ICAM-1 and ICAM-2 was strengthened in the slow loading regime by the addition of Mg(2+). Differences in the dynamic strength of the LFA-1/ICAM-1 and LFA-1/ICAM-2 interactions can be attributed to the presence of wider barriers in the ICAM-2 complex, making it more responsive to a pulling force than the ICAM-1 complex.
利用原子力显微镜（AFM）对表达于Jurkat T细胞上的白细胞功能相关抗原-1（LFA-1）与细胞间黏附分子-1和-2（ICAM-1和ICAM-2）之间的相互作用进行了单分子测量。在覆盖3个数量级（50 - 60,000 pN/s）的加载速率范围内获取了LFA-1/ICAM-1和LFA-1/ICAM-2相互作用的力谱（即解离力与加载速率），并揭示了快速加载模式和慢速加载模式。这表明两种复合物的解离都涉及克服一个陡峭的内部激活屏障和一个宽阔的外部激活屏障。在慢速加载模式下，通过添加Mg(2+)增强了LFA-1与ICAM-1和ICAM-2的结合。LFA-1/ICAM-1和LFA-1/ICAM-2相互作用的动态强度差异可归因于ICAM-2复合物中存在更宽的屏障，使其比ICAM-1复合物对拉力更敏感。
