Figure 1.

(A) Domains of the ETR1 protein. Hydrophobic, histidine kinase, and response-regulator domains are indicated. H indicates histidine-353, the putative phosphorylation site. G1 indicates position of the G1 box within the putative kinase domain. D indicates aspartate-659, a potential phosphorylation site. (B) Versions of ETR1 expressed as GST fusions in yeast. For truncations, the first and last amino acids of the expressed region are indicated, the full-length ETR1 protein being 738 amino acids long. For site-directed mutations, single letter abbreviations for amino acids Ala (A), Asn (N), Asp (D), Gln (Q), Gly (G), and His (H) are used.