Foroni L, Boehm T, White L, Forster A, Sherrington P, Liao X B, Brannan C I, Jenkins N A, Copeland N G, Rabbitts T H
MRC Laboratory of Molecular Biology, Cambridge, U.K.
J Mol Biol. 1992 Aug 5;226(3):747-61. doi: 10.1016/0022-2836(92)90630-3.
The rhombotin (RBTN1 or Ttg-1) gene was first identified at a chromosome translocation in a T-cell acute leukaemia and later used to isolate two related genes (RBTN2 or Ttg-2 and RBTN3). Complete characterization of these genes in man and mouse shows that all three encode cysteine-rich proteins with typical LIM domains. RBTN1 and RBTN3-derived proteins have 98% identity in the LIM domains but are located on separate chromosomes in man and in mouse while RBTN1 and RBTN2, both located on human chromosome 11p but are on separate chromosomes in mouse, are only 48% identical in this part of the protein. The exon organization of RBTN1 and RBTN3 genes are similar, both having an intron, absent from the RBTN2 gene, in the LIM2-encoding region. The remarkable similarity between rbtn-1 and rbtn-3 proteins is parallelled in their expression patterns in mouse development, since both genes show high expression in restricted areas of the brain, but little lymphoid expression. rbtn-2 expression, however, is more ubiquitous. This gene shows a low level of thymus expression but high expression in fetal liver, adult spleen and B-cell lines, consistent with a role in B-cell development. These results suggest multiple cellular targets for the action of these proteins during development.
菱蛋白（RBTN1 或 Ttg-1）基因最初是在一例 T 细胞急性白血病的染色体易位中被鉴定出来的，后来被用于分离两个相关基因（RBTN2 或 Ttg-2 以及 RBTN3）。对这些基因在人和小鼠中的完整表征表明，这三个基因均编码具有典型 LIM 结构域的富含半胱氨酸的蛋白质。RBTN1 和 RBTN3 衍生的蛋白质在 LIM 结构域中具有 98%的同一性，但在人和小鼠中位于不同的染色体上，而 RBTN1 和 RBTN2 虽都位于人类染色体 11p 上，但在小鼠中位于不同染色体上，在该蛋白质的这一部分仅具有 48%的同一性。RBTN1 和 RBTN3 基因的外显子组织相似，二者在编码 LIM2 的区域都有一个 RBTN2 基因所没有的内含子。rbtn-1 和 rbtn-3 蛋白之间的显著相似性在它们于小鼠发育过程中的表达模式中也有体现，因为这两个基因在大脑的特定区域都有高表达，但在淋巴组织中的表达很少。然而，rbtn-2 的表达更为普遍。该基因在胸腺中的表达水平较低，但在胎肝、成年脾脏和 B 细胞系中高表达，这与它在 B 细胞发育中的作用相符。这些结果表明在发育过程中这些蛋白质有多个细胞作用靶点。
