Figure 1

A) Amino acid sequences for IfkA and IfkB. The sequence for IfkA is shown in full. The first 898 amino acids that are not found in IfkB are boxed. For the remainder of the sequence, amino acid residues that differ between the two proteins are given in bold (IfkA) with the corresponding amino acid for IfkB shown underneath; a "-" indicates residues not found in IfkB. B) Schematic structures of IfkA, IfkB and GCN2 of yeast. Conserved regions are shown in black or striped. These include the pseudokinase domain, the kinase domain, and the histidyl-tRNA synthetase (HisRS) domain, including the m1-m3 motifs of the HisRS domain. The open regions inside the kinase domains are the insert sequences between the 4th and 5th kinase subdomain and are not conserved among GCN2 genes from different species. The final black box at the C-terminus of yeast GCN2 indicates a cluster of positively charged residues which are thought to function in ribosome binding and dimerization. No similar sequence was identified in this region within the Dictyostelium genes.