Genomic structure, alternative transcripts and chromosome location of the human LIM domain binding protein 1 gene LDB1

By protein interaction screening using a radioactive LMO2 protein probe we have isolated a LIM domain binding protein. The gene shows high homology to independently isolated genes from mouse, Xenopus and Drosophila called Ldb1/Nli/Clim-2, Xldb1 and Chip, respectively. The human and mouse genes differ by only two amino acids, suggesting that the gene that we have isolated is the human homologue. Here we describe the genomic organization, alternative transcript forms and the chromosome mapping of the human gene LDB1 (alias NLI). The gene is spread over at least 12 kb and has 11 exons. Preceding the described ATG initiation site in the mouse a highly conserved region between mouse, chicken and human was detected with a second possible in frame initiation site coding for further 36 amino acids. An alternative splice site adding six nucleotides corresponding to the addition of two amino acids at the end of exon 10 was found. The gene was mapped to chromosome 10q24-->q25 by in situ hybridization, a region frequently deleted in many types of cancer. Fine mapping with a radiation hybrid panel localized the gene in the interval between the markers D10S603 and D10S540.