Nucleotide sequence of mouse SCIP cDNA, a POU-domain transcription factor.
Nucleotide sequence of mouse SCIP cDNA, a POU-domain transcription factor.
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小鼠 SCIP cDNA（一种 POU 域转录因子）的核苷酸序列。
DOI：
10.1093/nar/19.4.956
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发表时间：
1991
影响因子：
14.9
通讯作者：
Magnuson,MA
中科院分区：
文献类型：
--
作者：
Zimmerman,EC;Jones,CM;Fet,V;Hogan,BL;Magnuson,MA
SCIP（Tst-1）是一种在神经组织和睾丸中表达的POU结构域转录因子。tst-1首先从大鼠睾丸中克隆出来，并发现在那里以及胚胎和成人大脑中的神经元的有限子集中表达（1）。随后，从大鼠坐骨神经cDNA文库中分离出称为SCIP（用于抑制cAMP诱导型POU）的cDNA（2）。DNA序列分析表明，Tst-I和SCIP cDNA都是同一基因的产物（2，3）。已报道大鼠Tst-Ⅰ的部分氨基酸序列（1）和大鼠坐骨神经SCIP的全氨基酸序列（3）。大鼠蛋白的长度为451个氨基酸，含有POU特异性和POU同源结构域特异性区域，其与Pit-1、Oct-1、Oct-2和其他POU蛋白的等同区域相似（4，5，6）。然而，最高程度的相似性是与假定的神经转录因子Bmn-I和Brn-2（1）。我们利用简并引物PCR扩增得到一个POU同源结构域DNA片段，并用此DNA片段筛选了XGT 10中的6.5天小鼠胚胎cDNA文库。对6个分离株的分析表明，它们各自含有约1.6kb的cDNA片段。将一个cDNA克隆（#2 -4c）的片段连接到BluescriptM 13（-）和pEMBL 18和19中用于DNA序列分析。该片段长1516 bp，含有一个1347 bp的开放阅读框。总的来说，该序列具有高GC含量（72%），并且这在5 '端更明显（前100个碱基的85%）。该基因编码449个氨基酸，与大鼠SCIP基因的同源性为99.1%。只有一个氨基酸是不同的（位置97，丝氨酸甘氨酸），但有一个缺失的两个丙氨酸在多聚丙氨酸丰富的区域附近的N-末端，因此占较短的长度。小鼠蛋白质的POU结构域和POU同源结构域特异性区域与大鼠SCIP的那些相同。因此，克隆的cDNA似乎编码小鼠SCIP。该cDNA编码的蛋白质的几个特征如图所示。POU结构域（氨基酸240-319）和POU同源结构域（氨基酸335-396）位于C末端。多聚丙氨酸重复序列位于N末端附近，随后是6个多聚甘氨酸重复序列，每个重复序列含有4-6个甘氨酸。多聚脯氨酸和多聚组氨酸重复序列（各6个氨基酸）位于C末端附近。除了这些重复区域，蛋白质的整体组成偏向于这四种氨基酸。共有67个丙氨酸（14.9%）、84个甘氨酸（18.7%）、37个组氨酸（8.2%）和39个脯氨酸（8.7%）。事实上，超过一半（50.5%）的蛋白质由这四个残基组成。SCIP中这些重复结构域的功能意义尚不清楚，但已知其他转录因子含有类似的重复区域。
SCIP (Tst-i) is a POU domaintranscription factor expressed in neural tissue and testes. Tst-l was first cloned from rat testes and found to be expressed both there and in a restricted subset of neurons in embryonic and adult brain (1). Subsequently a cDNA termed SCIP (for suppressed cAMP inducible POU) was isolated from a rat sciatic nerve cDNA library (2). DNA sequence analysis has shown that both the Tst-I and SCIP cDNAs are products of the same gene (2, 3). A partial amino acid sequence for rat Tst-I (1) and a full amino acid sequence for rat sciatic nerve SCIP (3) have been reported. The rat protein is 451 amino acids in length and contains both POU-specific and POU-homeodomain-specific regions that are similar to the equivalent regions ofPit-i, Oct-i, Oct-2 and other POU proteins (4, 5, 6). The highest degree of similarity, however, is to the putative neural transcription factors Bmn-I and Brn-2 (1). We obtained a POU-homeo domain DNA fragment by PCR amplification using degenerate primers and used this DNA fragment to screen a 6.5 day mouse embryo cDNA library in XGT1O. Analysis of six isolates showed they each contained a cDNA fragment of approximately 1.6 kb. Fragments of one cDNA clone (# 2-4c) were ligated into Bluescript M13 (-) and pEMBL 18 and 19 for DNA sequence analysis. The fragment was 1516bp in length and contained an open reading frame of 1347 bp. Overall the sequence had a high GC content (72%), and this was even more pronounced at the 5'end (85% ofthe first 100 bases). The protein encoded was 449 amino acids in length and was 99.1% homologous with rat SCIP. Only one amino acid was different (position97, serine to glycine) but there was a deletion of two alanines in the poly-alanine rich region near the N-terminus, thus accounting for the shorter length. The POU-domain and POU homeodomain-specific regions of the mouse protein are identical to those of rat SCIP. The cDNA cloned therefore appears to encode mouse SCIP. Several features of the protein encoded by this cDNA are illustrated in the Figure. The POU-domain (amino acids 240-319) and the POU homeo-domain (amino acids 335-396) are located towards the C-terminus. A poly-alanine repeat is located near the N-terminus followed by 6 poly-glycine repeats, each of which contains 4-6 glycines. A poly-proline and polyhistidine repeat (6 amino acids each) are located near the C-terminus. In addition to these repetitive regions, the overall composition of the protein is biased in favor of these four amino acids. In total there are 67 alanines (14.9%), 84 glycines (18.7%), 37 histidines (8.2%), and 39 prolines (8.7%). Indeed, just over half (50.5%) of the protein is composed of these four residues. The functional significance of these repetitive domains in SCIP is unknown but other transcription factors are known to contain similar repetitive regions.