Williams C J, Wreschner D H, Tanaka A, Tsarfaty I, Keydar I, Dion A S
Center for Molecular Medicine and Immunology, Newark, NJ 07103.
Biochem Biophys Res Commun. 1990 Aug 16;170(3):1331-8. doi: 10.1016/0006-291x(90)90540-4.
Cloning and sequencing of epithelial membrane antigen (EMA) has demonstrated the existence of a variable number of tandem repeats (VNTR) flanked by unique sequences, and alternative splicing has been proposed to result in secreted and membrane-bound antigenic forms. Antisense oligonucleotides, specific for the VNTR region and various alternative splice forms, were used as probes to define EMA transcripts in poly A+ RNA from a mucinous breast tumor cell line. The BT549 line has been shown to exhibit enhanced expression and secretion of EMA when the cells are cultivated in a medium supplemented with hydrocortisone and insulin, and Northern blot analysis demonstrated that EMA-related RNA transcripts are commensurately enhanced. As a result of the large increase in EMA RNA levels, two major transcripts in BT549 have been identified as coding for either the secreted or transmembrane EMA forms and two antigenic forms have been immunoprecipitated from BT549 cell layer and medium translation products.
上皮膜抗原（EMA）的克隆和测序表明，存在可变数量的串联重复序列（VNTR），其两侧为独特序列，并且有人提出可变剪接会产生分泌型和膜结合型抗原形式。针对VNTR区域和各种可变剪接形式的反义寡核苷酸被用作探针，以确定来自黏液性乳腺肿瘤细胞系的多聚A+RNA中的EMA转录本。当细胞在添加了氢化可的松和胰岛素的培养基中培养时，BT549细胞系已显示出EMA表达和分泌增强，Northern印迹分析表明EMA相关的RNA转录本相应增强。由于EMA RNA水平大幅增加，已在BT549中鉴定出两种主要转录本，分别编码分泌型或跨膜型EMA形式，并且已从BT549细胞层和培养基翻译产物中免疫沉淀出两种抗原形式。
