Figure 1.

Examples of Drosophila HLH proteins. Schematic depiction of Drosophila HLH proteins belonging to different classes. Da is an E-protein and Sc is an activator, encoded by a gene in the ASC. Emc is a negative regulator that lacks a basic domain. Hairy and E(spl)Mγ are two members of the Hairy/E(spl) class of negative regulators. Structural motifs are marked: b, basic domain; HLH, helix-loop-helix domain; LZ, putative leucine zipper; AD, conserved acidic domain among the ASC proteins; Or, Orange domain; and W, terminal WRPW tetrapeptide conserved among Hairy/E(spl) class members.