Genomic structure of the TACC genes. Conserved regions known to bind protein factors in all human TACC proteins are shown. The SDP repeat of human TACC1-3 is known to bind GAS41 ([3,15] and data not shown). The TACC domain binds ch-TOG and members of the Aurora kinases in all species examined to date. This motif is characteristically encoded by the 3' exons of the TACC genes. The size of the largest isoform for each gene is shown.