A segment polarity gene in Drosophila located at 2–62.0. In an organ that has undergone developmental compartmentalization (q.v.), such as an imaginal disc (q.v.) of a wing, en + functions as a selector gene (q.v.) that directs cells in a posterior compartment to form the posterior structures, rather than anterior structures, and to avoid mixing with anterior cells. Cells in the anterior compartment do not require en +. The en + gene encodes a homeobox (q.v.) protein that contains 552 amino acids and acts as a transcription regulator. The gene is expressed in many different tissues of the embryo and larva. Homologs of en occur in Caenorhabditis, the mouse, and humans. See Chronology, 1975, Morata and Lawrence.
Subjects: Genetics and Genomics.