One of the homeotic mutations (q.v.) of Drosophila which belongs to the Antennapedia complex. The homeotic mutations figure shows a normal fly head with its proboscis extending downward (A). The proboscis ends with a pair of labial palps which function in eating and taste. In the pb mutant (C) the proboscis has been transformed into a pair of legs. Therefore pb normally functions as a segment identity gene (q.v.). See Antennapedia, Hox genes.
Subjects: Genetics and Genomics.