Xie J, Zhang B, Lan M S, Notkins A L
Experimental Medicine Section, Oral Infection and Immunity Branch, Bethesda, Maryland, 20892-4322, USA.
Genomics. 1998 Dec 1;54(2):338-43. doi: 10.1006/geno.1998.5583.
IA-2 is a transmembrane protein tyrosine phosphatase, expressed in neuroendocrine cells, and a major autoantigen in insulin-dependent diabetes mellitus. In the present study we elucidated the structure of the IA-2 gene (HGMW-approved symbol PTPRN) and its promoter sequence. A 40-kb genomic clone covering the whole IA-2 coding sequence and 4 kb proximal 5'-upstream sequence was isolated and mapped. The IA-2 gene encompasses approximately 20 kb with 23 exons ranging from 34 bp to more than 650 bp. The extracellular domain is encoded by exons 1-12, the transmembrane region by exon 13, and the intracellular domain by exons 14-23. The transcriptional start site(s) of the IA-2 gene was mapped by 5' rapid amplification of cDNA ends to 97 bp upstream of the translational start site. A 3-kb 5'-upstream region was sequenced, revealing a GC-rich region and TATA-less sequence containing several potential transcription-regulating sites (i.e., Sp1, CREB, GATA-1, and MZF). Functional promoter activity was confirmed by transient transfection of U87MG cells with deletion mutants linked to a luciferase reporter gene.
IA-2是一种跨膜蛋白酪氨酸磷酸酶，在神经内分泌细胞中表达，是胰岛素依赖型糖尿病中的主要自身抗原。在本研究中，我们阐明了IA-2基因（HGMW批准符号为PTPRN）的结构及其启动子序列。分离并定位了一个覆盖整个IA-2编码序列和4 kb近端5'上游序列的40 kb基因组克隆。IA-2基因约含20 kb，有23个外显子，长度从34 bp到650 bp以上不等。细胞外结构域由外显子1至12编码，跨膜区域由外显子13编码，细胞内结构域由外显子14至23编码。通过5' cDNA末端快速扩增将IA-2基因的转录起始位点定位到翻译起始位点上游97 bp处。对一个3 kb的5'上游区域进行了测序，发现了一个富含GC的区域和一个无TATA序列，其中包含几个潜在的转录调控位点（即Sp1、CREB、GATA-1和MZF）。通过用与荧光素酶报告基因相连的缺失突变体瞬时转染U87MG细胞，证实了功能性启动子活性。
