Fig. 4. LHW gene and protein structure, and its behavior in a two-hybrid screen. (A) LHW gene structure, with exons represented as boxes and introns as lines. The LHW coding region is in black. The location and nature of lhw mutant alleles is indicated above the exons. (B) LHW protein structure. Two domains that are conserved with other plant proteins are indicated as grey boxes. Part of the C-terminal conserved region resembles the bHLH domain of transcriptional regulators. A sequence alignment of the putative bHLH domain (boxed) is diagrammed for LHW and for related proteins from Arabidopsis and rice. (C) Graphical representation of LHW protein fragments used in the yeast two-hybrid assay and their ability to dimerize with full-length LHW. (D) GAL4 transcriptional activation activity of LHW variants; pACT is included as a negative control. GUS measurements are based on four replicates/sample. Error bars ±s.e.m. NT, not tested.