The MPN+ motif. Sequence alignment of representative MPN domain protein, only two conserved blocks containing the MPN+ motif are shown. The proteins are grouped in seven categories: A, bacterial; B, archaeal; C, proteasome lid components; D, CSN components; E, eIF3 components; F, Prp8-like proteins; G other eukaryotic MPN proteins. In the eukaryotic groups, representative sequences from human (HS), Arabidopsis (AT), S. pombe (SP) and S. cerevisiae (SC) are shown. Prokaryotic species shown are lambda phage (BPL), Yersinia pestis (YP), Synechocystis sp. (SS), Mycobacterium tuberculosum (MyT), Pseudomonas aeruginosa (PA), Pyrococcus horikoshii (PH), Archaeoglobus fulgidus (AF), Methanobacter thermoautotrophicum (MT). Residues invariant or conservatively substituted in at least 50% of all sequences are shown on black and grey background, respectively. The MPN+ motif residues are shown in red. The top line indicates the amino acids constituting the MPN+ motif; the rightmost column indicates whether a protein is considered an MPN+ protein or a plain MPN protein.