首页>
外文期刊>The biochemical journal
>Cell surface-mediated activation of progelatinase A: demonstration of the involvement of the C-terminal domain of progelatinase A in cell surface binding and activation of progelatinase A by primary fibroblasts
【24h】
Cell surface-mediated activation of progelatinase A: demonstration of the involvement of the C-terminal domain of progelatinase A in cell surface binding and activation of progelatinase A by primary fibroblasts
pWe report that the isolated C-terminal domain of progelatinase A is inhibitory to the activation of this proenzyme by primary skin fibroblast plasma membranes but is unable to inhibit organomercurial-induced self-cleavage and activation. Ligand binding studies demonstrate that fibroblasts stimulated with concanavalin A to activate progelatinase A have a significantly enhanced level of cell surface-associated progelatinase A. Tissue inhibitor of metalloproteinases-2 (TIMP-2), an effective inhibitor of membrane-mediated progelatinase A activation, is able to abolish the enhanced level of cell surface-associated progelatinase A that occurs following stimulation. TIMP-1, a poor inhibitor of membrane activation, is unable to inhibit the cell surface binding of progelatinase A. The enhancement in the binding of 125I-progelatinase A to fibroblasts following concanavalin A stimulation can be blocked by the inclusion of excess C-terminal gelatinase A but not by a truncated form of gelatinase A lacking the C-terminal domain. Scatchard analysis of the binding of 125I-progelatinase A to concanavalin A-stimulated fibroblasts has identified 950,000 gelatinase binding sites per cell with a Kd of 1.3 x 10(-8) M. Analysis of non-stimulated fibroblasts has identified 500,000 sites per cell with a Kd of 2.6 x 10(-8) M. We propose that membrane-mediated activation of progelatinase A involves binding of the proenzyme through its C-terminal domain to the cell surface and that TIMP-2 can inhibit activation by interaction with progelatinase A through the C-terminal domain, thus preventing binding of the proenzyme./p
展开▼
机译：>我们报道，分离的明胶酶A的C末端结构域抑制了原皮肤皮肤成纤维细胞质膜对该酶的激活，但不能抑制有机汞诱导的自我切割和激活。配体结合研究表明，用伴刀豆球蛋白A刺激以激活明胶酶A的成纤维细胞具有显着提高的细胞表面相关明胶酶A的水平。金属蛋白酶2（TIMP-2）的组织抑制剂，一种膜介导的明胶酶A激活的有效抑制剂，能够消除刺激后细胞表面相关的明胶酶A水平的提高。 TIMP-1是一种弱的膜活化抑制剂，不能抑制明胶酶A的细胞表面结合。伴刀豆球蛋白A刺激后125I-明胶酶A与成纤维细胞结合的增强可通过包含过量的C末端来阻止明胶酶A，但不是缺少C末端结构域的明胶酶A的截短形式。对125 I-明胶酶A与伴刀豆球蛋白A刺激的成纤维细胞结合的Scatchard分析已鉴定出每个细胞950,000个明胶酶结合位点，Kd为1.3 x 10（-8）M.对非刺激性成纤维细胞的分析已鉴定出每个细胞500,000个位点。 Kd为2.6 x 10（-8）M。我们建议膜介导的明胶酶A活化涉及通过其C末端结构域与细胞表面结合的酶，TIMP-2可以通过与明胶酶A相互作用来抑制活化通过C端结构域，从而阻止了酶的结合。
展开▼
