Blaurock M C, Rebouças N A, Kusnezov J L, Igarashi P
Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520-8029, USA.
Biochim Biophys Acta. 1995 Jun 9;1262(2-3):159-63. doi: 10.1016/0167-4781(95)00075-r.
NHE1 (gene symbol SLC9A1) encodes an isoform of the amiloride-sensitive Na+-H+ exchanger that is present in many cells and the basolateral membrane of renal epithelia. Expression of NHE1 is modulated in response to chronic metabolic acidosis, growth factors, and phorbol esters. To begin examining the molecular basis for this regulation, a rabbit genomic clone that contained 6 kb of 5' flanking region, the first exon, and a portion of the first intervening sequence of NHE1 was obtained. The principal transcription start site in native rabbit tissues was located 798 bp 5' to the initiation codon. The sequence of the proximal 5' flanking region of rabbit NHE1 was similar to the human sequence and contained a TATA-box, (G + C)-boxes, homopyrimidine direct repeats, and a putative AP-1 site. When ligated to luciferase and transfected into porcine renal epithelial cells (LLC-PK1), 708 bp of proximal 5' flanking region exhibited orientation-dependent promoter activity.
NHE1（基因符号SLC9A1）编码一种对阿米洛利敏感的Na⁺-H⁺交换体的异构体，该交换体存在于许多细胞以及肾上皮细胞的基底外侧膜中。NHE1的表达会因慢性代谢性酸中毒、生长因子和佛波酯而受到调节。为了开始研究这种调节的分子基础，获得了一个兔基因组克隆，该克隆包含6 kb的5'侧翼区域、第一个外显子以及NHE1的第一个内含子序列的一部分。天然兔组织中的主要转录起始位点位于起始密码子上游798 bp处。兔NHE1近端5'侧翼区域的序列与人类序列相似，包含一个TATA框、（G + C）框、同嘧啶直接重复序列和一个假定的AP-1位点。当与荧光素酶连接并转染到猪肾上皮细胞（LLC-PK1）中时，近端5'侧翼区域的708 bp表现出方向依赖性启动子活性。
