Stage, tissue, and cell specific distribution of alternative Ultrabithorax mRNAs and protein isoforms in the Drosophila embryo

The homeotic gene Ultrabithorax encodes a family of six homeoproteins translated from alternatively spliced mRNAs. The structures of these UBX isoforms have been conserved among anciently diverged Drosoph-ila species and functional distinctions between some isoforms have been reported that suggest subtle but important roles in Ubx action. We present a detailed analysis of the expression patterns of Ubx mRNAs and proteins during embryogenesis, using isoform-specific monoclonal antibodies and synthetic oligonucleotide probes. These patterns are remarkably complex, each mRNA and corresponding protein isoform being expressed in a partially overlapping but distinct stage and tissue-specific patt…