Identification of VPCact. (A) Schematic representation of the reporter series, each with an internal 20-bp deletion, derived from the minimal construct identified in Figure 2G and here as construct 1. The lack of expression in reporters 2 and 3 define VPCact. VPCrep (red box) is intact; the green box shows the inferred position of VPCact based on these deletions, corresponding to the deleted region in construct 2 and the boxed region in B. (B) Alignments of VPCrep and VPCact sequences in lag-2, apx-1, and dsl-1 from C. elegans C. briggsae, C. brenneri, and C. remanei. Red box, VPCrep (Elk1 site). Green box, sequence deleted in reporter 2. Sequences similar to VPCact were not identified in the 5′ flanking regions of other C. elegans dsl genes (X. Zhang, unpublished observations).