DETECTION OF P-GLYCOPROTEIN ISOFORMS BY GENE-SPECIFIC MONOCLONAL-ANTIBODIES
DETECTION OF P-GLYCOPROTEIN ISOFORMS BY GENE-SPECIFIC MONOCLONAL-ANTIBODIES
复制标题
DOI：
10.1073/pnas.87.1.152
复制
发表时间：
1990-01-01
影响因子：
11.1
通讯作者：
LING, V
中科院分区：
文献类型：
--
作者：
GEORGES, E;BRADLEY, G;LING, V
P-糖蛋白是一种高度保守的膜蛋白，在许多多药耐药肿瘤细胞系中过表达。P-糖蛋白在哺乳动物细胞中由一个小基因家族编码。I类和II类异构体引起多药耐药，而III类则不会。在这份报告中，我们的特点是三个P-糖蛋白特异性单克隆抗体（单克隆抗体）的高分辨率表位映射与一系列的六肽。mAb C494具有基因特异性，可结合仅存在于仓鼠和人I类同种型中的序列。mAb C32识别仓鼠I类和II类同种型中的保守序列，但不识别III类同种型中的保守序列。相比之下，单克隆抗体C219识别在迄今为止表征的所有P-糖蛋白亚型中发现的高度保守的氨基酸序列。这些单克隆抗体被用来揭示差异表达和特异性定位的三个P-糖蛋白亚型在仓鼠组织中的免疫组化染色和竞争与表位特异性肽。结肠上皮细胞主要以极化方式表达I类亚型，肾上腺皮质细胞主要表达II类亚型，而一小部分骨骼肌纤维表达III类亚型P-糖蛋白。这些研究结果表明，P-糖蛋白异构体有不同的生理作用与专门的细胞功能。
P-glycoprotein is a highly conserved membrane protein shown to be overexpressed in many multidrug-resistant tumor cell lines. P-glycoprotein is encoded by a small gene family in mammalian cells. Class I and II isoforms cause multidrug resistance, whereas class III does not. In this report, we have characterized three P-glycoprotein-specific monoclonal antibodies (mAbs) by high-resolution epitope mapping with a series of hexapeptides. mAb C494 is gene specific, binding to a sequence present only in the class I isoform of hamster and human. The mAb C32 recognizes a sequence conserved in hamster class I and II isoforms but not in class III isoforms. In contrast, the mAB C219 recognizes a highly conserved amino acid sequence found in all P-glycoprotein isoforms characterized to date. These mAbs were used to reveal differential expression and specific localization of the three P-glycoprotein isoforms in hamster tissues by immunohistochemical staining and competition with epitope-specific peptides. Colonic epithelial cells expressed predominantly the class I isoform in a polarized manner, adrenal cortical cells expressed predominantly the class II isoform, whereas a small percentage of skeletal muscle fibers expressed the class III isoform of P-glycoprotein. These findings suggest that the P-glycoprotein isoforms have distinct physiological roles associated with specialized cell functions.