Hoeppner M A, Gilbert D J, Copeland N G, Jenkins N A, Linzer D I, Wu B
Department of Biochemistry, Northwestern University, Evanston, IL 60208 USA.
Nucleic Acids Res. 1996 Mar 15;24(6):1091-8. doi: 10.1093/nar/24.6.1091.
Isolation of cDNA clones for the mouse CCAAT binding factor (mCBF) has revealed the expression of two distinct forms of mCBF that are generated by alternative splicing of a single primary transcript from a gene that maps to chromosome 17. The mCBF1 mRNA encodes a protein of 997 amino acids, whereas the mCBF2 protein is predicted to be only 461 amino acids in length; mCBF1 and human CBF (hCBF) share>80% amino acid sequence identity. Analysis of adult mouse tissue RNAs has revealed that the mCBF1 and mCBF2 mRNAs are ubiquitously expressed, but that mCBF1 mRNA is 5- to 10-fold more abundant than mCBF2 mRNA. Similarly, mCBF mRNA was detected through-out the placenta and in all tissues of the developing embryo from day 8 to day 18 of gestation. Overexpression of the two forms of mCBF in mammalian cells has demonstrated that the mCBF1 and mCBF2 proteins localize to different cellular compartments, with mCBF1 found predominantly in the nucleus and mCBF2 restricted to the cytoplasm. Co-expression of these two forms influences their localization, however, indicating that CBF activity can be regulated by the relative amounts of the two forms expressed in a cell.
小鼠CCAAT结合因子（mCBF）cDNA克隆的分离揭示了两种不同形式的mCBF的表达，它们是由位于17号染色体上的一个基因的单一初级转录本通过可变剪接产生的。mCBF1 mRNA编码一种含997个氨基酸的蛋白质，而mCBF2蛋白质预计长度仅为461个氨基酸；mCBF1与人类CBF（hCBF）的氨基酸序列同一性超过80%。对成年小鼠组织RNA的分析表明，mCBF1和mCBF2 mRNA广泛表达，但mCBF1 mRNA的丰度比mCBF2 mRNA高5至10倍。同样，在整个胎盘以及妊娠第8天到第18天发育胚胎的所有组织中都检测到了mCBF mRNA。在哺乳动物细胞中过表达这两种形式的mCBF表明，mCBF1和mCBF2蛋白质定位于不同的细胞区室，mCBF1主要存在于细胞核中，而mCBF2局限于细胞质中。然而，这两种形式的共表达会影响它们的定位，这表明CBF活性可以由细胞中表达的两种形式的相对量来调节。
