Exd
Exd, short for extradenticle, is a developmental transcription factor best known for its role as a cofactor of Hox proteins in Drosophila melanogaster and other species. It helps specify segment identity along the anterior–posterior axis by modulating the activity and target selection of Hox transcription factors, thereby influencing patterns of tissue and organ formation.
Exd proteins belong to the TALE (three amino acids loop extension) class of homeodomain proteins. As a
A key aspect of Exd function in Drosophila is its subcellular localization. Exd is predominantly cytoplasmic
vertebrate homologs of Exd are the PBX family (PBX1–PBX4), which partner with Meis proteins and HOX
Exd is a foundational example of a transcription factor that does not act alone but as a