Abstract
The Sex combs reduced (Scr) homeotic gene of Drosophila melanogaster specifies the development of structures within the most posterior head segment, the labium and the most anterior thoracic segment, the prothorax or T1. Here, the structure of Scr and correct sequence of the SCR protein are presented. Scr encodes a 417-amino-acid DNA-binding protein with sequence similarity to the mouse homologues, HOXA5, B5 and C5. The greatest similarity is within the DNA-binding homeodomain (hdm); shorter conserved motifs are found near the N terminus and a region N-terminal to the hdm. As with most of the D. melanogaster homeotic genes, Scr has alternative exons.
