Fig. 1

Structural models of Gal4 and Zal1; the experimental expression concept. a Structural model of Gal4 protein domains in the native homodimeric configuration; two zinc fingers constitute the DNA-binding domain. Only the DNA-binding domain, linker and dimerization domain of Gal4 are shown. b A hypothetical expression pattern for Gal4 homodimer driving expression from a UASG effector gene in the adult fly brain. c. A hypothetical structural model of Zal1 protein in which the zinc fingers of Gal4 are replaced with fingers 1 and 2 from the crystal structure of EGR1, shown in red. d A hypothetical expression pattern for Zal1 homodimer driving expression from a UASZ effector gene. e A model of the Gal4-Zal1 heterodimer. f A hypothetical expression pattern produced by Gal4-Zal1 heterodimer in the presence of a UASGZ effector gene