Regulation and Products of the Ubx Domain of the Bithorax Complex

Abstract

The cluster of homeotic genes known as the bithorax complex (BX-C) (Lewis 1978) is divisible into three complementation groups, or functional domains (Sánchez-Herrero et al. 1985). Each domain provides the major developmental determinants for segment identity in one of three adjacent metameric regions that together extend from the anterior/posterior compartment boundary (a/p) of the second thoracic segment (T2) into the eighth abdominal segment (A8) (Fig. 1). Thus, the Ultrabithorax (Ubx) domain controls the T2p-Ala region (Lewis 1963, 1978, 1981, 1982; Morata and Kerridge 1981; Hayes et al. 1984; Struhl 1984; Sánchez-Herrero 1985 and this volume), and the abdominal-A (abd-A) and Abdominal-B (Abd-B) domains control the Alp-A4 and A5–A8 regions, respectively (Sánchez-Herrero et al. 1985).