与肿瘤转移抑制基因nm_（23）高度同源的nm_（23）－H_3b基因的克隆和

Cloning and sequencing of nm23-H3b, a new gene i-dentified to nm23

ｎｍ＿（２３）是一种有效的肿瘤转移抑制基因，目前已发现的两种人类ｎｍ＿（２３）（Ｈ＿１和Ｈ＿２）的氨基酸肽具有８８％的同源性。我们采用ＰＣＲ技术从人肝基因组ＤＮＡ中扩增ｎｍ＿（２３）序列，经克隆筛选得到５’端３７５ｂｐ克隆，命名为ｎｍ＿（２３）－Ｈ３ｂ。序列分析发现，ｎｍ２３－Ｈ＿３ｂ在４０ｂｐ～７０ｂｐ之间与原序列完全不同，其他序列与ｎｍ＿（２３）－Ｈ１有８６％的同源性，与ｎｍ＿（２３）－Ｈ２有９０％的同源性。ＢｇｌＩＩ消化人肝基因组ＤＮＡ，用ｎｍ＿（２３）－Ｈ＿３ｂＤＮＡ为探针，经ＳｏｕｔｈｅｒｎＢｌｏｔ后发现１０．５、７．９和４．０ｋｂ的３条杂交带，未见与ｎｍ＿（２３）－Ｈ＿１和Ｈ＿２相同的杂交带。因此认为ｎｍ＿（２３）－Ｈ＿３ｂ是一种与人肿瘤转移抑制基因ｎｍ＿（２３）－Ｈ＿１和Ｈ＿２高度同源的新基因克隆。

m23 is a kind of an effective tumor metastasissuppressor gene which included two types in human :nm23-H1 and nm23-H2. Amino acid identrty betweennm23-H1 and nm23-H2 was 88%. In this study, weused a pair of primers to flank the part of coding se-quence of nmes. The 5’-translated sequence was am-plified by PCR from hurnan normal liver genomicDNA. A 375bp clone was characterized to designatepnm 23-H3b. The nm23-H3b nucleotide sequence be-tween 40bp and 70bp was different from nm23-H1 andnm23-H2, and other sequences had 86% and 90% i-dentical to nm23-H1 and nm23-H2, respectively.Southern blot containing Bg1II-digested human livergenomic DNA hybridized to the entire nm23-H3b DNAand showed three bands at 10.5, 7.9 and 4.0 kb.These data demonstrate that nm23-H3b is a new typeof gene, which has high homology with human nm23-H1 and nm23-H2. Nm23 is possibly considered a familyof closely related genes.