Cloning and characterization of the gene encoding murine insulin-like growth factor-binding protein-2, mIGFBP-2

We present a characterization of the single-copy gene, mIGFBP-2, encoding the murine insulin-like growth factor-binding protein-2 (mIGFBP-2). It consists of four exons with sizes of 470 +/- 2, 227, 141 and > 475 nucleotides (nt). The first intron spans 23 kb of genomic sequence, and the complete gene extends to more than 28 kb. Two kb of the 5'-flanking region were sequenced. This region has no TATA or CAAT boxes but is G+G-rich and contains several potential regulatory sequence motifs. A total of five GC boxes, which may serve as potential binding sites for a transcription factor, Sp1, are present immediately upstream of the transcription start point (tsp). By primer extension, we identified a single tsp at nt position -85 +/- 2. The murine IGFBP-2 locus was mapped to the proximal region of mouse chromosome 1, to a region of conserved synteny with human chromosome 2q. A comparison of the deduced amino acid sequences of mouse, rat and human IGFBP-2 reveals a high degree of homology between all three species.