Asker C E, Magnusson K P, Piccoli S P, Andersson K, Klein G, Cole M D, Wiman K G
Microbiology and Tumor Biology Center, Karolinska Institute, Stockholm, Sweden.
Oncogene. 1995 Nov 16;11(10):1963-9.
B-myc is a member of the myc gene family. Previous studies indicate that the rat B-myc gene contains a single exon which shows 77% nucleotide homology to the second exon of the rat c-myc gene. Its open reading frame (ORF) encodes a polypeptide with a predicted molecular weight of 20 kD. We have isolated a new, larger rat B-myc genomic clone. Sequence analysis of this clone confirmed the presence of one single coding exon. Furthermore, a genomic mouse B-myc clone was identified and compared to the rat homolog. Nucleotide analysis of B-myc coding and non-coding sequences suggests that it may be a functional gene evolved by selective duplication of part of the second c-myc exon. Analysis of the rodent B-myc open reading frames revealed two in-frame amino acid duplications in mouse B-myc and a 96% conservation at the amino acid level. Both rat and mouse B-myc proteins contain an identical and unique stretch of 14 carboxy terminal amino acid residues not found in other myc proteins. In vitro translation of rat and mouse B-myc ORF's yielded proteins that migrated as 26 kD bands in SDS-PAGE and could be immunoprecipitated by a polyclonal panmyc antiserum. Immunostaining of human lymphoma cells transiently transfected with a B-myc expression vector showed that the protein was mainly localized to the nucleus.
B - myc是myc基因家族的成员。先前的研究表明，大鼠B - myc基因包含一个单一外显子，该外显子与大鼠c - myc基因的第二个外显子具有77%的核苷酸同源性。其开放阅读框（ORF）编码一种预测分子量为20 kD的多肽。我们分离出了一个新的、更大的大鼠B - myc基因组克隆。对该克隆的序列分析证实了存在一个单一的编码外显子。此外，鉴定了一个基因组小鼠B - myc克隆并与大鼠同源物进行了比较。对B - myc编码和非编码序列的核苷酸分析表明，它可能是通过部分第二个c - myc外显子的选择性复制进化而来的一个功能基因。对啮齿动物B - myc开放阅读框的分析揭示了小鼠B - myc中有两个框内氨基酸重复，并且在氨基酸水平上有96%的保守性。大鼠和小鼠的B - myc蛋白都含有一段相同且独特的14个羧基末端氨基酸残基序列，这在其他myc蛋白中未发现。大鼠和小鼠B - myc ORF的体外翻译产生的蛋白质在SDS - PAGE中迁移为26 kD条带，并且可以被多克隆泛myc抗血清免疫沉淀。用B - myc表达载体瞬时转染的人淋巴瘤细胞的免疫染色显示，该蛋白主要定位于细胞核。
