IDENTIFICATION OF A NEW HUMAN nm23 GENE,nm23-H3b

Nm23 is a kind of effective tumor metastasis suppressor genes which included two types in human:nm23-H1 and nm23-H2. Amino acid identity between nm23-H1 and nm23-H2 was 88%.In this study,using a pair of primers to flank the part of coding sequence of nm 23,the 5'-translated sequence was amplified by polymerase chain reaction (PCR) from human normal liver genomic DNA.A 375-base pairs clone was charactertzed,which designated pnm23-H3b.The nm23-H3b nucleotide sequence between 40 bp and 70 bp is different from nm23-H1 and nm23-H2,and other sequences have 86%and 90%identical to nm23-H1 and nm23-H2,respectively.Southern blot containing BglⅡ-digested human liver genomic DNA hybridized to the entire nm23-H3b DNA and showed three bands at 10.5,7.9 and 4.0 Kb.These data demonstrate that the third human nm23 exists possibly.Therefore,nm23 may be considered a family of closely related genes.

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

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。