(A), C-Terminal sequences of CAO of Arabidopsis, Chlamydomonas and Prochlorothrix. Vertical lines indicate conserved residues. The conserved tyrosine (Y) residue, identified in Figure 6 as labeled with 125I-, is marked with an asterisk. At, Arabidopsis thaliana; Cr, Chlamydomonas reinhardtii; Ph, Prochlorothrix hollandica. (B), The evolutionary relationship between CAO and other proteins that contain non-heme iron and Rieske domains. Examples of the sequence surrounding the site of the conserved tyrosine, indicated in (A), are illustrated for a representative protein in each clade. (Cladogram from ref. , used with permission).