STEROID INTERACTIONS WITH P GLYCOPROTEINS

描述（改编自申请人摘要）：mdr 1 P-糖蛋白可能调节小鼠T淋巴瘤细胞对 糖皮质激素 P-糖蛋白是ATP依赖性转运蛋白， 疏水性药物从细胞中释放，从而引起多药耐药性。 一些 类固醇如孕酮抑制药物通过P-糖蛋白的转运。 在P-糖蛋白的能力中存在高度的选择性， 运输皮质类固醇，类固醇的特定结构特征是 识别决定簇结合和运输的P-糖蛋白。 本申请提出了鼠mdr 1的结构-功能分析， 与皮质类固醇结合和运输能力有关的蛋白质。 一 已经开发了一种方法来选择WEHI-7小鼠T细胞的变体， 含有mdr 1突变的淋巴瘤细胞系影响蛋白质 运输地塞米松。 通常抑制mdr 1的其他类固醇具有 在这种变体中这样做的能力降低。 这些选择旨在 确保耐多药1型药物保持其大部分转运其他药物的能力。 它 mdr 1基因突变可能影响对 特定的类固醇结构特征是结合的决定因素， mdr1。 使用多种类固醇mdr 1抑制剂的试验将确定 这些类固醇结构决定因素（最初，3-和 20-酮基）不再被突变的MDR 1识别。 体外 突变MDR 1蛋白的诱变和表达将证实 每个突变的功能效应。

DESCRIPTION (Adapted from the applicant's abstract): The mdr1 P-glycoprotein may regulate the sensitivity of murine T lymphoma cells to glucocorticoids. P-glycoproteins are ATP-dependent transporters that remove hydrophobic drugs from cells and thus cause multidrug resistance. Some steroids such as progesterone inhibit transport of drugs by P-glycoproteins. There is a high degree of selectivity in the ability of P-glycoproteins to transport corticosteroids, and specific structural features of steroids are recognition determinants for binding to and transport by P-glycoproteins. This application proposes a structure-function analysis of the murine mdr1 protein concerning its ability to bind to and transport corticosteroids. A method has been developed to select for variants of the WEHI-7 murine T lymphoma line that contain mdr1 mutations affecting the protein's ability to transport dexamethasone. Other steroids that normally inhibit mdr1 have a reduced capacity to do so in such variants. The selections are designed to ensure that mdr1 retains most of its capacity to transport other drugs. It is proposed that the putative mdr1 mutations affect the recognition of specific steroid structural features that are determinants for binding to mdr1. Assays using a variety of steroidal mdr1 inhibitors will determine which of these steroid structural determinants (initially, the 3- and 20-keto groups) are no longer recognized by the mutated mdr1. In vitro mutagenesis and expression of mutant mdr1 proteins will confirm the functional effects of each mutation.