MOUSE BRACHYURY-THE-SECOND (T2) IS A GENE NEXT TO CLASSICAL-T AND A CANDIDATE GENE FOR TCT

The mouse Brachyury the Second (T2) gene is 15 kb away from classical Brachyury (T). A mutation in T2 disrupts notochord development, pointi ng to the existence of a second T/t complex gene involved in axis deve lopment. T2 encodes a novel protein that is disrupted by an insertion in T2(Bob) mice. Sequence analysis of T2 from several t haplotypes sho ws that they all share the same changed stop codon, and, thus, T2 is a candidate gene for the t complex tail interaction factor. T1, T2, and the unlinked t-int are distinct and unrelated loci, and mutations in these genes do not complement one another genetically. Either their pr oducts interact in the same pathway during the genesis of the embryoni c axis, or the T/t region itself is truly complex.