Ingvarsson S, Asker C, Axelson H, Klein G, Sümegi J
Department of Tumor Biology, Karolinska Institute, Stockholm, Sweden.
Mol Cell Biol. 1988 Aug;8(8):3168-74. doi: 10.1128/mcb.8.8.3168-3174.1988.
The myc family of genes contains five functional members. We describe the cloning of a new member of the myc family from rat genomic and cDNA libraries, designated B-myc. A fragment of cloned B-myc was used to map the corresponding rat locus by Southern blotting of DNA prepared from rat X mouse somatic cell hybrids. B-myc mapped to rat chromosome 3. We have previously mapped the c-myc to rat chromosome 7 (J. Sümegi, J. Spira, H. Bazin, J. Szpirer, G. Levan, and G. Klein, Nature [London] 306:497-498, 1983) and N-myc and L-myc to rat chromosomes 6 and 5, respectively (S. Ingvarsson, C. Asker, Z. Wirschubsky, J. Szpirer, G. Levan, G. Klein, and J. Sümegi, Somat. Cell Mol. Genet. 13:335-339, 1987). A partial sequence of B-myc had extensive sequence homology to the c-myc protein-coding region, and the detection of intron homology further indicated that these two genes are closely related. The DNA regions conserved among the myc family members, designated myc boxes, were highly conserved between c-myc and B-myc. A lower degree of homology was detected in other parts of the coding region in c-myc and B-myc not present in N-myc and L-myc. A 1.3-kilobase B-myc-specific mRNA was detected in most rat tissues, with the highest expression in the brain. This resembled the expression pattern of c-myc, although at different relative levels, and was in contrast to the more tissue-specific expression of N-myc and L-myc. B-myc was expressed at uniformly high levels in all fetal tissues and during subsequent postnatal development, in contrast to the stage-specific expression of c-myc.
myc基因家族包含五个功能成员。我们描述了从大鼠基因组和cDNA文库中克隆出的myc家族新成员，命名为B-myc。通过对大鼠与小鼠体细胞杂交制备的DNA进行Southern印迹分析，利用克隆的B-myc片段来定位相应的大鼠基因座。B-myc定位于大鼠3号染色体。我们之前已将c-myc定位于大鼠7号染色体（J. Sümegi、J. Spira、H. Bazin、J. Szpirer、G. Levan和G. Klein，《自然》[伦敦]306:497 - 498，1983年），将N-myc和L-myc分别定位于大鼠6号和5号染色体（S. Ingvarsson、C. Asker、Z. Wirschubsky、J. Szpirer、G. Levan、G. Klein和J. Sümegi，《体细胞与分子遗传学》13:335 - 339，1987年）。B-myc的部分序列与c-myc蛋白编码区具有广泛的序列同源性，内含子同源性的检测进一步表明这两个基因密切相关。myc家族成员间保守的DNA区域，即myc框，在c-myc和B-myc之间高度保守。在c-myc和B-myc编码区中不存在于N-myc和L-myc的其他部分检测到较低程度的同源性。在大多数大鼠组织中检测到一种1.3千碱基的B-myc特异性mRNA，在脑中表达最高。这类似于c-myc的表达模式，尽管相对水平不同，并且与N-myc和L-myc更多的组织特异性表达形成对比。与c-myc的阶段特异性表达相反，B-myc在所有胎儿组织以及随后的出生后发育过程中均以均匀的高水平表达。
