Aoto H, Miyake Y, Nakamura M, Tajima S
Institute for Protein Research, Osaka University, Japan.
Genomics. 1997 Feb 15;40(1):138-41. doi: 10.1006/geno.1996.4546.
The AZ1 protein is localized to the preacrosome region of spermatids. Previous developmental studies suggested that AZ1 gene transcription begins in pachytene spermatocytes and that expression of the gene is induced in cultivated fibroblasts on treatment with 5-azacytidine, which is known to lead to the demethylation of genomic DNA. In the present study, we cloned the gene coding AZ1 cDNA and elucidated its genomic organization. AZ1 cDNA was encoded by 25 exons distributed within 25 kb of genomic DNA. The transcription started at nucleotide positions -312 and -311 of the cDNA, with the A of the ATG codon specifying the initiator methionine assigned as nucleotide position +1. Exon 1 and a part of intron 1 of the AZ1 gene constituted a typical CpG island, and an about 0.2-kb sequence of the 5'-proximal region exhibited a G + C content and CpG ratio higher than the averages for the mammalian genomic sequence.
AZ1蛋白定位于精子细胞的前顶体区域。先前的发育研究表明，AZ1基因转录始于粗线期精母细胞，并且在用5-氮杂胞苷处理培养的成纤维细胞时会诱导该基因的表达，已知5-氮杂胞苷会导致基因组DNA去甲基化。在本研究中，我们克隆了编码AZ1 cDNA的基因并阐明了其基因组结构。AZ1 cDNA由分布在25 kb基因组DNA内的25个外显子编码。转录起始于cDNA的核苷酸位置-312和-311，ATG密码子的A指定起始甲硫氨酸，其被指定为核苷酸位置+1。AZ1基因的外显子1和内含子1的一部分构成了一个典型的CpG岛，5'-近端区域的约0.2 kb序列显示出高于哺乳动物基因组序列平均值的G + C含量和CpG比率。
