Popielarz M, Cavaloc Y, Mattei M G, Gattoni R, Stévenin J
Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Illkirch, France.
J Biol Chem. 1995 Jul 28;270(30):17830-5. doi: 10.1074/jbc.270.30.17830.
The 9G8 factor is a 30-kDa member of the SR splicing factor family. We report here the isolation and characterization of the human 9G8 gene. This gene spans 7745 nucleotides and consists of 8 exons and 7 introns within the coding sequence, thus contrasting with the organization of the SC35/PR264 or RBP1 SR genes. We have located the human 9G8 gene in the p22-21 region of chromosome 2. The 5'-flanking region is GC-rich and contains basal promoter sequences and potential regulatory elements. Transfection experiments show that the 400-base pair flanking sequence has a promoter activity. Northern blot analysis of poly(A)+ RNA isolated from human fetal tissues has allowed us to identify five different species, generated by alternative splicing of intron 3, which may be retained or excised as a shorter version, as well as the use of two polyadenylation sites. We also show that the different isoforms are differentially expressed in the fetal tissues. The persistence of sequences between exon 3 and 4 results in the synthesis of a 9G8 protein lacking the SR domain which is expected to be inactive in constitutive splicing. Thus, our results raise the possibility that alternative splicing of intron 3 provides a mechanism for modulation of the 9G8 function.
9G8因子是SR剪接因子家族中一个30 kDa的成员。我们在此报告人类9G8基因的分离与特性。该基因跨度为7745个核苷酸，编码序列内由8个外显子和7个内含子组成，这与SC35/PR264或RBP1 SR基因的结构不同。我们已将人类9G8基因定位在2号染色体的p22 - 21区域。其5'侧翼区域富含GC，包含基础启动子序列和潜在调控元件。转染实验表明，400个碱基对的侧翼序列具有启动子活性。对从人类胎儿组织中分离的聚腺苷酸化RNA进行Northern印迹分析，使我们鉴定出五种不同的类型，它们是由内含子3的可变剪接产生的，内含子3可以保留或被切除为较短的形式，同时还存在两个聚腺苷酸化位点的使用。我们还表明，不同的异构体在胎儿组织中差异表达。外显子3和4之间序列的保留导致合成一种缺乏SR结构域的9G8蛋白，预计该蛋白在组成型剪接中无活性。因此，我们的结果提出了内含子3的可变剪接为调节9G8功能提供一种机制的可能性。
