TFPIalpha and TFPIbeta

描述（由申请方提供）：组织因子途径抑制剂（TFPI）是因子VIIa/组织因子诱导凝血的体内抑制剂，因此，在调节因子VIIa/组织因子作用的凝血和炎症效应中发挥关键的生理作用。我们最近发现，两种形式的TFPI蛋白，产生的mRNA剪接，在人类细胞中表达。这两种形式都以糖基磷脂酰肌醇（GPI）锚定的方式与细胞表面结合，但机制不同。TFPI-alpha是一种可溶性蛋白质，似乎与另一种GPI锚定蛋白结合，而TFPI-beta含有内在的GPI锚。该提案的主旨是表征和对比TFPI-α和TFPI-β的位置、功能活性和潜在生理作用。在我们的具体目标中，我们提出：1）比较TFP-alpha和TFPI-β的表达; 2）确定介导其细胞表面结合的TFPR-alpha的结构组分; 3）鉴定和表征TFPI-alpha表面结合蛋白; 4）比较细胞表面TFPI-alpha和TFPI-β以及可溶性TFPI-alpha的活性;和5）研究TFPI GPI-锚定的体内相关性。

DESCRIPTION (provided by applicant): Tissue factor pathway inhibitor (TFPI) is the in vivo inhibitor of factor VIIa/tissue factor-induced coagulation and, as such, plays a critical physiologic role in regulating the coagulant and inflammatory effects of factor VIIa/tissue factor action. We have recently shown that two forms of the TFPI protein, produced by alternative mRNA splicing, are expressed in human cells. Both forms associate with the surface of cells in a glycosylphosphatidylinositol (GPI)-anchored fashion, but through different mechanisms. TFPI-alpha, a soluble protein, appears to bind to another GPI-anchored protein(s), whereas TFPI-beta contains an intrinsic GPI-anchor. The thrust of this proposal is to characterize and contrast the location, functional activity, and potential physiologic roles of TFPI-alpha and TFPI-beta. In our specific aims we propose to: 1) Compare the expression of TFP-alpha and TFPI-beta; 2) Determine the structural components of TFPR-alpha that mediate its cell surface binding; 3) Identify and characterize the TFPI-alpha surface binding protein(s); 4) Compare the activities of cell-surface TFPI-alpha and TFPI-beta, and soluble TFPI-alpha; and 5) Investigate the in vivo relevance of TFPI GPI-anchorage.