Analysis of two-dimensional dissociation constant of laterally mobile cell adhesion molecules
Analysis of two-dimensional dissociation constant of laterally mobile cell adhesion molecules
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DOI：
10.1529/biophysj.106.089649
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发表时间：
2007-02-01
影响因子：
3.4
通讯作者：
Golan, David E.
中科院分区：
文献类型：
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作者：
Zhu, De-Min;Dustin, Michael L.;Golan, David E.
我们制定了一个一般的分析，以确定二维解离常数（2D K-d），并使用这种方法来研究CD 2表达T细胞与玻璃支持的平面双层含有荧光标记的CD 58，CD 2的反受体的相互作用。CD 2和CD 58在它们各自的膜中都是横向移动的。粘附是由CD 2和CD 58在细胞双层接触面积的积累，粘附分子密度和接触面积的大小达到平衡40分钟内。标准（Scatchard）分析的溶液相结合是不适用于横向移动的粘附分子的情况下，由于相互作用的动态性质。推导出一个新的结合方程：B/F [（N-t × f）/（K-d × S-cell）] - [（B × p）/K-d]，其中B和F分别为接触面积中结合和游离的CD 58密度，N-t为每个细胞中CD 2分子数，f为CD 2迁移率分数，S-cell为细胞表面积，p为平衡时与S-cell的接触面积之比。我们使用该分析确定CD 2-CD 58的2D Kd为5.4-7.6分子/μ m（2）。2D K-d分析提供了调节细胞-细胞粘附机制的一般和定量测量。
We formulate a general analysis to determine the two-dimensional dissociation constant (2D K-d), and use this method to study the interaction of CD2-expressing T cells with glass-supported planar bilayers containing fluorescently labeled CD58, a CD2 counter-receptor. Both CD2 and CD58 are laterally mobile in their respective membranes. Adhesion is indicated by accumulation of CD2 and CD58 in the cell-bilayer contact area; adhesion molecule density and contact area size attain equilibrium within 40 min. The standard (Scatchard) analysis of solution-phase binding is not applicable to the case of laterally mobile adhesion molecules due to the dynamic nature of the interaction. We derive a new binding equation, B/F [(N-t x f)/(K-d x S-cell)] - [(B x p)/K-d], where B and F are bound and free CD58 density in the contact area, respectively; N-t is CD2 molecule number per cell; f is CD2 fractional mobility; S-cell is cell surface area; and p is the ratio of contact area at equilibrium to S-cell. We use this analysis to determine that the 2D K-d for CD2-CD58 is 5.4-7.6 molecules/mu m(2). 2D K-d analysis provides a general and quantitative measure of the mechanisms regulating cell-cell adhesion.