Taylor J D, Wellman S E, Marzluff W F
J Mol Evol. 1986;23(3):242-9. doi: 10.1007/BF02115580.
The sequences of four histone H3 genes coding for the replication variant proteins H3.1 and H3.2 have been determined. Three of these genes, two coding for H3.1 proteins and one for an H3.2 protein, are located on chromosome 13 and expressed at low levels. The fourth gene, encoding an H3.2 protein, is located on chromosome 3 and expressed at a high level. The coding regions of the three genes on chromosome 13 are more similar to each other than to the H3 gene on chromosome 3, and equally divergent from it, suggesting that either gene duplication or gene conversion has occurred since the genes were dispersed onto two chromosomes. A 14-base sequence including the CCAAT sequence and located 5' to the genes on chromosome 13 has been conserved. The histone H3 gene on chromosome 3 has multiple potential binding sites for the Sp1 transcription factor. The coding regions show greater than 95% conservation among the four genes. This is due to the strict pattern of codon usage and the presence of two long (greater than 60 base) regions of completely conserved nucleic acid sequence. These conserved regions in the coding sequence may have an important functional role at the mRNA or DNA level.
已确定了编码复制变体蛋白H3.1和H3.2的四个组蛋白H3基因的序列。其中三个基因，两个编码H3.1蛋白，一个编码H3.2蛋白，位于13号染色体上，表达水平较低。第四个基因，编码H3.2蛋白，位于3号染色体上，表达水平较高。13号染色体上的三个基因的编码区彼此之间比与3号染色体上的H3基因更相似，且与它的差异程度相同，这表明自这些基因分散到两条染色体上以来，要么发生了基因复制，要么发生了基因转换。一个包含CCAAT序列且位于13号染色体上基因5'端的14碱基序列得以保留。3号染色体上的组蛋白H3基因有多个Sp1转录因子的潜在结合位点。四个基因的编码区显示出大于95%的保守性。这是由于严格的密码子使用模式以及存在两个完全保守的核酸序列的长（大于60个碱基）区域。编码序列中的这些保守区域可能在mRNA或DNA水平上具有重要的功能作用。
