FIGURE 1.

Phylogeny and variation of beta proteasome subunits of tomato. (A) Phylogenetic tree of beta subunit genes of tomato and Arabidopsis. Neighbor-joining tree of protein sequences was build using ClustalW2. (B) Summary of the variant amino acid residues that differ between β2a and β2b. e, putative solvent-exposed. Significant variation is printed in bold. (C) Location of variant residues in β2, modeled on the yeast proteasome. The tomato β2a protein was modeled using the β2 of yeast (2zcy) as a template. Residues that differ between β2a and β2b are highlighted in red in the topview (top) and sideview (bottom) of the β-ring of the proteasome and summarized in the table. The proteolytic chamber is highlighted with a dashed orange line and catalytic sites are indicated with orange arrows. (D) Transcript levels of β subunit-encoding genes in various tomato organs. These data were extracted from The Tomato Genome Consortium (2012). Reads per kilobase of transcripts per million mapped reads (RPKM) values were extracted from the database for each gene.