The Hox 1.3 Horneo Box Gene Encodes a Sequence Specific DNA Binding Phosphoprotein

The murine Hox 1.3 homeo box gene is the third member of the Hox 1 cluster, located on chromosome 6 (Colberg-Poley et al., Bucan et al.). Analysis of the Hox 1.3 cDNA and genomic sequences indicate that its major transcript of 1.85 Kb (detected in both embryonic and adult tissues) encodes a 270 amino acid homeo domain protein (Odenwald et al.). Our previous studies suggested that the Hox 1.3 protein present in cultured fibroblasts may be post-translationally modified (i.e., aberrant migration and multiple immunoreactive forms in SDS gels). In order to obtain sufficient amounts of the Hox 1.3 protein to study its biology, we have employed the Baculovirus expression system. In addition to high levels of protein expression, this eukaryotic system has been shown to perform correct post-translational modification of nuclear proteins (Miyamoto et al.).