Characterization and chromosomal localization of the human insulin-like growth factor-binding protein 6 gene

Insulin-like growth factor-binding protein 6 (IGFBP6), an extracellular protein with preferential affinity for insulin-like growth factor (IGF) II, belongs to a family of binding proteins with at least six members. We have characterized the genomic structure and the chromosomal location of the human IGFBP6, which is present in the human genome as a single-copy gene spanning 4.7 kb. It consists of four exons, encoding the translated regions, with sizes of 334, 146, 120, and 123 bp, while the intervening introns are 2661, 182, and 844 bp. Three mRNA cap sites were localized 101, 100, and 96 bp upstream of the ATG translation start codon as determined by S1 nuclease analysis. The proximal 5'-flanking region does not have any TATA or CAAT consensus sequences. The IGFBP6 was localized to Chr 12 by analysis of somatic cell hybrids and regionalized to 12q13 by fluorescence DNA in situ hybridization.