a. Prediction model for the transmembrane topology of HvHMA2.

<p>Schematic diagram illustrating predicted TMs and key motifs. Residues shown in TMs are postulated to coordinate metals during transport. For HvHMA2 the putative cytoplasmic C-terminal metal-binding domain is 307 aa including 56 His and 18 Cys residues plus 4 Cys pairs. Amino acid numbers relevant to the deletion and substitution mutants are included. b. Dendrogram of P_1B-ATPases. Includes: all rice and Arabidopsis P_1B-ATPases, best available barley sequences and predicted P_1B-2-ATPases identified through Aramemnon for maize, Brachypodium and sorghum. The P_1B-2 (Zn/Cd) ATPase subgroup is circled, and the sub-set with >17% His residues in the predicted C-termini is indicated. Those P_1B-2-ATPases that do not fall within this subset feature <9% His residues in the predicted C-termini. Partial sequences are indicated. Scale bar indicates amino acid substitutions per site.