The human TBX6 gene: cloning and assignment to chromosome 16p11.2

Tbx6 is a member of the T-box family of proteins, which share a region of homology corresponding to the DNA-binding domain of the transcription factor T. Previous expression studies and knockout experiments in mice indicate that Tbx6 is important for specification of paraxial mesoderm structures. We have isolated and characterized the human orthologue, TBX6. Sequence comparisons show that overall the nucleotide homology between human and mouse TBX6/Tbx6 is 84%; within the T-box there is 89% nucleotide homology and 96% amino acid identity. TBX6 maps to chromosome 16 p11.2, a region syntenic with mouse chromosome 7, at 61 cM, the map position of mouse Tbx6. RT-PCR studies of RNA distribution indicate that this gene is expressed not only during gastrulation but has a second phase of expression in some adult tissues including testis. DNA/protein-binding studies demonstrate that Tbx6 binds to the same target DNA as T protein and can form a dimeric complex with DNA. We could find no evidence that Tbx6 forms a heterodimer with T.