The site of RUB-conjugation is highly conserved among cullins from diverse organisms. Residues conserved with AtCUL1 are in bold. Boxes indicate residues that are identical in all proteins shown. AtBAC-ChrI (A. thaliana, GenBank accession no. AC002330), CeCUL-4 (Caenorhabditis elegans, GenBank accession no. U58086), MmCUL-1 (Mus musculus, GenBank accession no. AF083216), At-BAC-ChrV (A. thaliana, GenBank accession no. AB025620), HsCUL-1 (Homo sapiens, GenBank accession no. AF062536), HsCUL-4A (H. sapiens, GenBank accession no. U58090), LeCUL (Lycopersicon esculentum, European Molecular Biology Laboratory accession no. Y16124), DmChr2 (Drosophila melanogaster, accession no. AC005473), HsCul-4B (H. sapiens, accession no. U58091), CeCUL-1 and -2 (C. Elegans, accession nos. U58083 and U58085), HsCUL3 and -2 (H. Sapiens, accession nos. U58089 and gbU83410), and CeCUL-2 (C. Elegans, accession no. U58084).