Figure 4.

Conserved sequence features of chloroplast response regulators. The receiver domain of the representatives ycf27, ycf29 and the Arabidopsis TCP34 are aligned with those of three canonical response regulators in bacteria ArcA, RegA and OmpR. Species names of ycf29 sequences are boxed. Predicted secondary structures are shown at the bottom. Conserved sequence motifs of the receiver domain, DD, D1 and K, are indicated on top of the alignment. The fully conserved D1 motif, which lies in the loop connecting the third beta sheet and the third helix, is the conserved aspartate residue that receives the phosphate group from the phosphohistidine of the sensor kinase. Arabidopsis TCP34 shows a moderately conserved receiver domain with the ‘K motif’ still being present, but not entirely aligned with those from other response regulators.