Patel P I, Framson P E, Caskey C T, Chinault A C
Mol Cell Biol. 1986 Feb;6(2):393-403. doi: 10.1128/mcb.6.2.393-403.1986.
The human hypoxanthine phosphoribosyltransferase (HPRT) gene has been characterized by molecular cloning, mapping, and DNA sequencing techniques. The entire gene, which is about 44 kilobases in length, is composed of nine exon elements. The positions of the introns within the coding sequence are identical to those of the previously-characterized mouse HPRT gene, although there are significant differences between intron sizes for the two genes. HPRT minigenes have been used in a transient expression assay involving microinjection into HPRT- cells to demonstrate functional promoter activity within a 234-base-pair region upstream from the ATG codon. The promoter of this gene resembles those of other recently characterized "housekeeping" genes in that it lacks CAAT- and TATA-like sequences, but contains several copies of the sequence GGGCGG. Both RNase protection and primer extension analysis indicate that human HPRT mRNA is heterogeneous at the 5' terminus, with transcription initiation occurring at sites located congruent to 104 to congruent to 169 base pairs upstream from the ATG codon. Comparison of the mouse and human HPRT 5'-flanking sequences indicates that there are only limited stretches of conserved sequence, although there are other shared features, such as an extremely high density of potential methylation sites, that may have functional significance.
人类次黄嘌呤磷酸核糖转移酶（HPRT）基因已通过分子克隆、定位和DNA测序技术进行了表征。整个基因长度约为44千碱基，由九个外显子元件组成。编码序列中内含子的位置与先前表征的小鼠HPRT基因相同，尽管这两个基因的内含子大小存在显著差异。HPRT微型基因已用于涉及显微注射到HPRT -细胞中的瞬时表达测定，以证明在ATG密码子上游234个碱基对区域内的功能性启动子活性。该基因的启动子与其他最近表征的“管家”基因的启动子相似，即它缺乏CAAT和TATA样序列，但含有几个GGGCGG序列拷贝。核糖核酸酶保护和引物延伸分析均表明，人类HPRT mRNA在5'末端是异质的，转录起始发生在与ATG密码子上游104至169个碱基对一致的位点。小鼠和人类HPRT 5'侧翼序列的比较表明，保守序列的延伸有限，尽管存在其他共同特征，例如潜在甲基化位点的极高密度，可能具有功能意义。
