Schematic of Expression Patterns of Regulatory Factors

Regulation of eve stripes 3 and 7 by a single enhancer

Expression patterns of the regulatory factors important for repressionof stripes 3 and 7 are shown schematically (A). Activation requires theactivity of a ubiquitous D-Stat protein under the control of thehopscotch JAK kinase pathway. Stripe 7 also requires Tll function foractivation. The two stripe pattern (B) is formed by selectiverepression that involves several factors at the poles including the gapprotein Hb. Repression between the stripes 3 and 7 is mediated by thegap protein Kni. Thus multiple repressors form the final pattern. Theactivator protein D-Stat and the gap proteins Kni and Hb bind to sitesin the 500 bp stripe 3+7 enhancer (C) that is sufficient for expressionof these two stripes in transgenic embryos. The relative positions ofbinding sites for D-stat (S), Hb (H), and Kni (K) proteins are shown.